Vol. 1. Part IIIMEMOIRS

OF THE

ROYAL SOCIETY OF SOUTH AUSTRALIA.

FOSSIL REMAINS OF LAKE CALLABONNA.

PART III

DESCRIPTION OF THE VERTEBRÆ

OF

GENYORNIS NEWTONI

BY

E. C. STIRLING, C.M.G., M.A., M.D., F.R.S., C.M.Z.S., Director,

AND

A. H. C. ZIETZ, F.I..S., C.M.Z.S., Assistant Director, South Australian Museum.

ADELAIDE:W. C. RIGBY, 74. King William Street.

Parcels for Transmission to the Royal Society of South Australia, from Europe and America, should be addressed “per W. C. Rigby, care Messrs. Thos. Meadows & Co .. 35, Milk Streer, Cheapside, London."

Vardon and Pritchard, Printers, Adelaide

DESRIPTION OF THE VERTEBRAEOF

GENYORNIS NEWTONIBy E. C. STIRLING, C.M.G., M.D., F.R.S., C.M.Z.S., Director,

and

A. H. C. ZIETZ, F.L.S., C.M.Z.S., Assistant Director, South Australian Museum.

Plates XXV.-XXXV.

(Read May, 1905)

ATLAS.Pl. XXV., figs. 1-4.

This bone is represented by two imperfect specimens. In each the hypophysial body representing the centrum is nearly perfect, but in neither has more than a small part of the neural arch been preserved.

Basing the general description upon the larger and, on the whole, more perfect example (Y), its preaxial* surface presents, for the occipital condyle, a deeply excavated, subcircular articular concavity (pl. XXV., figs. 2-4, A). This might have been described as cup-shaped but for the large vacuity for the reception of the odontoid process of the axis which cleaves the rim in the mid-dorsal region and encroaches on the floor to almost the centre of the concavity. Thus, by the intrusion of this notch, the actual bony surface for the condyle becomes crescentiform in shape, the horns of the crescent being, however, obtusely rounded and much incurved towards one another, approaching to within a distance of about 4 mm. The width of each horn where it is narrowest, which is at points situated a little ventrad of its extremity, is about two-thirds of the dorso-ventral diameter of the crescentiform surface.

The rim, or border, of the articular depression is most elevated in the median ventral region and the dorso-lateral margins of the two horns are also raised to about the same degree. In the mid-lateral region, between each horn and the more elevated ventral region, the rim is relatively depressed.

The notch, which has been described as cleaving the dorsal margin of the articular

* This term will be used to denote positions that in a vertical or horizontal spinal column would be called, respectively, "superior" or "anterior," while postaxial will be correspondingly used for what under similar circumstances would be termed "posterior” or “inferior.”

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concavity and encroaching on its floor, is narrow at its entrance where the dorsal horns of the crescentiform surface approach one another to within a distance of less than half their own breadth or, as has been stated, to within about 4 mm., but more ventrad the notch widens out, forming a deep oval excavation which extends to the centre of the surface.

In respect of the dorso-ventral depth of this excavation, the conditions of the fossil bone are more nearly paralleled in the atlas, of the Emeu (fig. 5) than in that of the Cassowary (fig. 6), Ostrich (fig. 7), or Rhea, in all of which latter the notch is more open and shallower.

In contour the rim of the concavity is approximately circular in the larger bone (Y), but in the smaller (figs. 1 and 2) the form is somewhat compressed laterally, or obtusely pyriform, so that, while its dorso-ventral diameter slightly exceeds this measurement in the former, its transverse width is distinctly less.

The postaxial surface of the centrum is in the better condition in the atlas (Y) and is that figured (fig. 4, B); it is, in the dorsal two-thirds of its extent, very slightly convex transversely, but distinctly so dorso-ventrally; the ventral border, however, is produced considerably postaxiad as well as slightly ventrad so as to form a somewhat prominent lip (C). This latter bears distinct indications of having, in its intact condition, possessed a decided median hypapophysial projection, though this has been lost by fracture; while, at the ventro-lateral angles, less marked projections have undergone some reduction by localised abrasion. In the specimen X the greater part of the ventral edge of this surface has been broken away and, in the little that is left, the indications of such a lip are much less marked.

The neural surface of the centrum, scarcely more than half the pre-postaxial length of the ventral, is slightly convex in that direction along the mid-line, while, transversely, it is concave, the curvature being determined by the inward and upward sweep of the two horns, the preaxial faces of which form part of the occipital articular surface. No mark or pit for ligamentous attachment is visible.

The hæmal surface of the body, the pre-postaxial length of which is about double that of the neural, is generally, but very gently, convex transversely and very slightly concave along the opposite axis; it slopes ventrad as it proceeds postaxiad, thereby increasing the dorso-ventral width of the postaxial surface as compared with that of the preaxial. A slight rising begins about the middle of the pre-postaxial median line of this (postaxial) surface, which gains in saliency as it proceeds towards the postaxial border, and, had this rising not shared the abrasion mentioned in connection with the ventral border of the postaxial surface, it would probably have constituted more or less of a distinct ventrally and postaxially directed humal spine.

The lateral surface of the body (fig. 2, D) is nearly flat both in the dorso-ventral and pre-postaxial diameters, and, dorsad, is evenly continuous with the outer surface of the

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pedicle while, ventrad, the hinder borders are continuous with the lateral prominences mentioned in connection with the ventral lip of the postaxial surface.

The neural arch of atlas Y retains only a short portion (7 mm.) of the left pedicle (figs. 1 and 2, E), while in specimen X it exists to the extent of 18 mm. on the right side.

In the latter, that which remains of the process in question is a laterally compressed bar of inconsiderable pre-postaxial breadth. Its preaxial border rises from the outer margin of a small flat surface, homotypal with the prezygapophyses, which surmounts the overarching horns that bound the antarticular vacuity, and as this border ascends it slopes slightly postaxiad. The postaxial border springs from the body a little preaxiad of the dorsal border of the postarticular surface and ascends almost directly dorsad. Thus, owing the inclination postaxiad of the preaxial border, the pedicle narrows as it ascends, and, viewed from its pre- or postaxial aspect, the process diverges slightly from the median longitudinal plane.

The conspicuous characters of this pedicle when compared with the homologous part in the Emeu, Cassowary, Ostrich and Rhea are its length and straightness. From a slight inclination inwards near the broken end of the pedicle in specimen y and from the position of the fracture on its internal aspect, it is probable that the process has been broken just where the lamina should be given off. Neither the pedicle nor the body, in either specimen, shows any trace of a bony bar or spicule which defines a vertebrarterial canal such as exists more or less completely in the atlantes of the struthious birds previously referred to.

TABLE SHOWING RELATIVE DIMENSIONS OF THE ATLAS IN GENYORNIS AND STRUTHIO (Measurement in millimetres)

-

Preaxial Surface. Postaxial Surface. Neural Surface.

Ventral Surface.

Maximum transverse

width.

Dorso-ventral do

Transverse width.

Dorso- ventral do

Pre- postaxial diameter.

Pre- postaxial diameter.

Genyornis “X" 17 19 21 - 10 -

Genyornis "Y" 20 18 25 15 10 18

Struthio camelus 12'5 9 12 4 5 6

MIDDLE CERVICAL VERTEBRA (A).Pl. XXV., figs. 8-1l.

This segment to which we assign a position corresponding to about the middle of the cervical series is, with the exception of the atlas, the most preaxially situated member of the spinal series that is in a condition admitting of adequate description. A few odd fragments may belong to a position earlier in the series, but they afford no indication of general characters, and may, therefore, be left out of consideration at present.

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The preaxial surface of the centrum (pl. XXV., figs. 8 and 10, A) is transversely extended, its side to side diameter, measured at its middle, being rather more than three times as great as the median dorso-ventral height. In the former direction it is considerably concave, in the latter very slightly convex. The dorsal margin of the surface is deeply concave at its centre, the curve being coincident with the sweep of the, here, circular neural canal, of which, indeed, it forms the preaxial margin. Lateral to this concavity the margin rises into prominent convexities. The ventral margin of the preaxial surface, of considerably greater lateral" extent than thl3 dorsal, is also concave, but its curvature forms an arc of a circle whose radius is more than twice that of the circle of which the median dorsal margin forms a part; moreover, in the case of the ventral margin the concavity is coincident with the whole transverse width, and not merely with the median region. The effect of the approach towards one another of these two concavities, dorsal and ventral, confers upon the preaxial surface, included between them somewhat of the form of a horizontally placed hour-glass, the borders of the two ends of which, however, are asymmetrical by reason of the inequality of the lengths of their dorsal and ventral curvatures.

The postaxial surface of the centrum (figs. 9 and 11, B) forms a subquadrate figure which is convex in the transverse and concave in the dorso-ventral direction, being thus reversely heterocoelous as compared with the opposite articular face.*

Its dorsal border, which is somewhat shorter than the ventral, is gently concave dorsad; in the latter, which, moreover, is produced more postaxially than the former (fig. 11), the median region only is concave ventrad, the radius of curvature of this part being also less than that of the dorsal marginal concavity. Lateral to the median concavity the ventral border forms ventrally directed convexities.

The lateral margins of the postaxial surface are nearly straight, but, from the greater width of the ventral border as compared with that of the dorsal, they diverge as they proceed from the latter towards the former. Measured in the mid-line the transverse breadth is nearly twice the dorso-ventral height. The absolute dimensions in this vertebra are as follows:-transverse diameter of dorsal border 25 mm., of ventral border 32 mm., median vertical diameter 16 mm.

The ventral surface of the centrum in this vertebra has suffered considerable damage. Its preaxial border, coinciding with the ventral border of the preaxial articular surface, is concave; the postaxial, similarly coincident with the ventral border of the hinder articular surface, is, when the vertebra is seen from a ventral point of view, convex. In front of this (postaxial) border the lateral margins of the ventral surface incline gently inwards towards one another as they advance and then curve outwards with greater abruptness to form the posterior borders of the parapophysial expansions. Beginning at the postaxial margin a shallow median longitudinal groove indents the under part of

* Unless otherwise stated, it will be understood that the reversely heterocœlous characters of the pre. and postaxial articular surfaces exist in subsequently described vertebrae.

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the ventral surface which, in. the front part, owing to the lateral and ventral expansion of the parapophyses, appears to acquire a greater width and depth. Moreover, while, in the hinder three-quarters, the longitudinal groove is parallel to the axis of the neural canal, in the front quarter of its extent it becomes gently inclined, dorsad, towards the latter, so that in a preaxial, end-on view of the vertebra, a little of the front part of the ventral surface of the centrum is visible. This feature, better marked in some subsequent vertebrae, is not shown very well here; still it is just observable in the darkly-shaded area below A in fig. 8. The abrasions suffered by this vertebra leave it uncertain whether parial hypapophyses* (catapophyses, + Mivart) existed, but if they did, which is probable, they must have been small and situated well on the under surfaces of the parapophyses, and, consequently, widely separated.

On the lateral aspect of this vertebra the pleurapophysial plate (Mivart ++), or lateral arch (Lydekker$), bounding the foramen transversarium, or vertebrarterial canal, has been entirely lost on one side, and on the other only a preaxial strip of it has been left (figs. 9 and 11, c). Judging, however, from the extent of its broken diapophysial and parapophysial attachments (see fig. 11, where the distance from J to K represents the extent of the parapophysial attachment) the pre-postaxial width of this plate would, if intact, have nearly equalled half the length of the centrum. The foramen itself (to the left of C, fig. 8 and to the right in fig. 9) is broadly ellipsoidal in contour and, in size, considerably exceeds the neural canal. There still remains at the hinder part of the broken surface that represents the parapophysial or ventral attachment of the lateral arch (at K in fig. 11) a minute postaxially directed spicule of bone as a remnant of a synostosed riblet. The lateral surface of the centrum itself (fig. 11, D) is nearly straight pre- and postaxially and slightly concave dorso-ventrally.

The neural canal (figs.8 and 9) is circular in section and the preaxial margin of its floor stands almost the length of its own diameter in advance of the corresponding margin of the neural roof. Similarly the postaxial margin of the floor projects beyond the corresponding margin of the roof, but to a considerably less extent. Expressed in another way, the fore-and-aft length of the roof of the neural canal is considerably less than that of the floor, the proportions being as 39 mm. to 67 mm.

The prezygapophyses (figs. 8 and 10, A Z), one of which has suffered some destruction of its outer part, have their articular surfaces oval in contour and nearly flat; and they face to about an equal extent mesiad and dorsad. Stretching from the outer and postaxial aspect of the prezygapophysis to the outer and preaxial region of the post zygapophysis is a slender bony bar (figs. 8, 10, 11, E) which leaves beneath it a considerable, oval-shaped interzygapophysial foramen. This bar is present only on the left side, its fellow having been lost by damage. * Trans. Zool. Soo., vol, IX., p. 260; vol. X., +. 158.t Trans. Zool. Soc., vol. VIII., p. 401.++ Trans. Zool. Soc. Vol. VIII., pp. 393, 396.$ Cat. Fossil Birds, Brit. Mus., 1891, p. 335.

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The postzygapophysial processes (figs. 8-11, p) are considerably elongated pre- and postaxially, being more than half the length of the centrum and their summits preserve a very uniform, and, in relation to the axis of the-neural canal, horizontal level. They are somewhat closely approximated and nearly parallel, diverging but very slightly postaxially. Their hinder extremities project for nearly half their length postaxiad of the hinder border of the roof of the neural canal, and, also, to a slight extent beyond the ventral lip of the posterior articular surface. Between these zygapophyses the neural roof forms the floor of a deep interzygapopliysial sulcus (figs. 9 and 10, F) which is open behind and, in front, is bounded by a low bony ridge (fig. 10, below F) joining the front ends of the two zygapophyses. This ridge appears from its developmental transition in subsequent vertebrae to represent the neural spine. The articular surfaces of the postzygapophyses (figs. 9 and 10, P Z) are suboval, nearly flat and slightly smaller than those of the prezygapophyses, and they lie nearly in the same plane as the latter. Hyperapophyses* are wanting.

The narrowing preaxial ends of the postzygapophyses are continued forwards in the same direction as slightly elevated ridges which converge like the arms of a y to unite in a broader and flat median elevation which may be likened to the stem of that Jetter (figs. 8 and 10, H); this is continued forwards till it meets the preaxial edge of the neural roof. Between the converging ridges is a small shallow depression (just above H in fig. 10); lateral to them, and occupying the regions between the anterior and posterior zygapophyses, are larger and deeper depressions that would admit the top of an average little finger (just lateral to H in fig. 10). The front edge of the neural roof forms an open concavity which springs on each side from about the middle of the mesial-ventral margins of the prezygapophyses. This edge, as we have elsewhere indicated in another way, stands considerably postaxiad of the corresponding edge of the floor of the canal.

Depressions which appear to be the orifices of pneumatic foramina are situated-one (below D in fig. 11) a little in advance of the middle of the lateral surface of the centrum just beneath, what would have been if this structure were complete, the hinder edge of the pleurapophysial band, and the other just beneath the front end of the bony bar which has been described as entering into the circumscription of the interzygapophysial foramen.

Two other vertebrae so closely resemble the foregoing that separate description is unnecessary.

MIDDLE CERVICAL VERTEBRA (B).Plate XXVI.

In this vertebra, which is somewhat damaged in its lateral parts, the differences from the segment previously described are such as to indicate that it is a somewhat later member of the cervical series. Its centrum is of the same fore-and-aft length as that of "A," but it is slightly broader and its two principal articular surfaces are distinctly larger, though

* Proc. Zool. Soc., vol VIII, p. 90.

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otherwise similarly formed. Both prezygapophyses are lost, but the hinder pair an~ shorter, broader, more divergent and bear broad low hyperapophyses (Pl. XXVI., P, P in fig. 3, and just above P, P, in figs. 2 and 5), while their articular surfaces (figs. 2 and 5, P Z) are both longer and broader than in "A." They lie, however, in a very similar plane.

The bar (fig. 3, N) closing the front of the sulcus (F) between the postzygapophyses is higher than in "A," and is here beginning to assume the form of a low neural spine wedged in between the anterior ends of the zygapophyses. Conformably with the greater divergence of the latter as compared with" A," the interzygapophysial sulcus is V-shaped in horizontal section, and, taking its floor as an index of its length, it is considerably shorter than in the previous vertebra.

As in " A " there is in this segment a similar convergence of the two low ridges continued forwards from the front ends of the postzygapophyses, but their descent is steeper and they enclose a wider angle; moreover, the single median ridge (H) leading preaxiad from their point of junction to the margin of the neural roof is narrower and less salient, while the depressions on each side are shallower.

The distance from the interzygapophysial bar, representing the neural spine, to the middle of the preaxial edge of the neural roof is greater than in "A," while that from the spine to the mid-point of the postaxial edge is less than in that vertebra. The total length, however, of the neural roof is the same as in "A," and bears about the same proportion to the neural floor. The preaxial margin of the neural roof forms here an obtusely angular outline (fig. 3, below H) rather than a curve as it does in the previously described vertebra.

The bony bars joining the anterior and posterior zygapophyses have been lost with the exception of a small portion of the hinder attachment of that of the right side (fig. 3, E).

On the ventral surface of the centrum (fig. 4) there is, on one side, enough left of the parapophysial expansion to show that low parial hypapophyses (catapophyses, Mivart) existed situated just at the place where the parapophyses spring from the body (fig. 4, R). The effect of the presence of these hypapophyses is to narrow and, to some extent, deepen the front end of the shallow median longitudinal groove described in connection with the ventral surface of "A." The neural canal is here almost truly circular but slightly smaller than in the previously described vertebra.

POSTERIOR CERVICAL VERTEBRAE (C.D.E.).The serial gradation in size and shape of the three vertebrae designated as "C.", "D." and

"E." together with their accurate fit and similarity in texture and color, suggest that they are consecutive segments in the same individual. We consider them to be almost, if not absolutely, the last of the true cervical series. On account of its superior condition, it will be convenient to base the general description upon "D," the

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middle member of the series, and afterwards to indicate those features in respect of which its supposed predecessor and successor differ from it.

“D”Pl. XXVIII.

The preaxial articular surface (pl. XXVIII., fig. I, A) presents on a larger scale the principal features of this region in vertebra "A," the chief difference being that the very well-defined ventral border, instead of being concave as in that vertebra, here lies nearly in a horizontal plane when the vertebra is laid on the table with the dorsal surface uppermost. The maximum transverse diameter of the surface, which corresponds to its ventral border, is 145 mm. as compared with 135 mm. in “A."

The postaxial articular surface (figs. 2 and 5, B) is also larger than in "A;" it also more nearly approaches to a rectangular figure than in that vertebra by reason of the equality of length of the dorsal and ventral borders and approximate parallelism of the sides. Both dorsal and ventral borders are, however, slightly concave, and both form rather prominent lips, the latter being the more salient (cf. fig. 5). Measured in the mid-transverse and mid-dorso-ventral axes the dimensions are 34 mm. and 23 mm. respectively.

The ventral surface of the centrum (fig. 4, v) is of about the same length as in “A" and "B," but its breadth exceeds that of the former considerably and that of the latter slightly. Allowing for the greater width of this surface its features are generally similar to those of its counterpart in the vertebrae mentioned, though the inclination, dorsad, of its front third is very much more marked than in either "A " or "B ;" thus, to a considerably greater extent than in these vertebrae, is the front part of the ventral surface of the centrum visible in a direct preaxial, end-on, view (see fig. I, v).

Of the catapophyses (fig. 4, RR) one has been entirely lost, while the other-that of the left side-is considerably abraded; but it is evident that they were situated nearer the middle line and, apparently, it would appear also more prominent than in the preceding vertebrae.

The lateral surfaces of the centrum are concave both in the fore-and-aft and 40rsoventral directions.

The lateral arch, or pleurapophysial plate, has been preserved, in part, on one side only (figs. 1,2, 5, C), but it has been crushed inwards with some loss of substance and otherwise considerably damaged, so that it is not possible to state exactly the antero-posterior width of the arch except at its diapophysial and parapophysial attachments. On these criteria the width of the arch appears to have been about the same as in "A." The presence of a riblet is again suggested by the spicular termination of the postaxial end of the broken parapophysial attachment (fig. 5, J, K). The compression to which the arch has been subjected has considerably altered the natural shape of the vertebrarterial canal, but, judging from the extent of one intact diameter, this opening would appear

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to have been considerably larger than the neural canal and slightly larger than the corresponding aperture in "A'"

The neural canal itself yields in section a very full ellipse with the longer diameter transverse (fig. 1). The preaxial margin of its floor stands at about the same distance' in advance of the margin of the roof as in "A," and the degree of projection of the hinder margin of the floor is also comparable to what obtains in that vertebra.

The prezygapophysial surfaces (fig. 3), ovoid and nearly flat, are slightly larger and much more widely separated than in "A;" like those of the latter, they face to about an equal degree mesiad and dorsad.

The postzygapophyses (figs. 1,2,3,5, P) are of about the same length and breadth as in "B," but they are much more widely separated, the space separating them, measured at the hinder part of the interzygapophysial cleft, being three times greater than in the vertebra referred to. There is also a progressively increased vertical elevation of the postzygapophyses above the neural roof, this being nearly three times as great as in "A," but only slightly greater than in "B;" their hinder limits, also, extend considerably postaxiad of the ventral lip of the postaxial articular surface of the centrum. The postzygapophysial facets (figs. 2 and 5, PZ) are ovo-pyriform with the smaller end behind, and they look rather more ventrad than externally.

Broad-based, uneven hyperapophyses, marked by the position of P in figs. 2, 3, and 5. surmount the zygapophyses and add distinctly to their vertical height.

Owing to the greater separation of the postzygapophyses, that which has been described in previous vertebra as the sulcus between them (fig. 3, F) has here rather more of the nature of a wide recess or fossa. The bony bar or bridge (fig. 2, N) connecting their front ends appears, here, distinctly as an obtusely conical neural spine wedged in between, buttressed by, and coalesced with the anterior ends of the zygapophyses; but its height is insignificant when compared with that of the latter processes.

The posterior surface of the spine appears as a broad, low vertical ridge, the summit of which appears, when the vertebra is viewed from behind, as a distinct elevation between the zygapophyses; this ridge, bounding the before-mentioned interzygapophysial fossa in front, slopes rather steeply postaxiad and ventrad to the roof of the neural canal; it disappears, however, with, or rather before, its subsidence on the roof.* From each side of this slightly projecting neural summit two low ridges (indistinctly shown in fig. 2 at M, M), proceed postaxiad along the inner sides of the postzygapophyses, on which they run out at about the vertical level of the neural roof. . These ridges may be said to constitute the upper lateral limits of the interzygapophysial fossa.

From a front, as well as from a posterior, view the neural spine (N) appears as a low, rounded prominence between the zygapophyses with which it has coalesced. The preaxial surface of the spine is defined by a barely perceptible median ridge (hardly visible

*Owing to the incidence of the light in the photographic reproduction, these features are not distinctly shown in Fig 2 at N

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at 0 in fig. 3) which gains in saliency, but loses in width, as it descends with an easy gradient to subside on the fiat platform formed by the anterior half-inch of the neural roof. Arising from, and forming the continuation of, the preaxial faces of the postzygapophyses are two low, obtuse ridges (fig. 3, SS) which descend, converging very slightly, at the same gradient as the front face of the neural spine and subside on the flat neural platform lateral to its median line and before reaching its front margin. Between these converging lateral ridges and the median ridge are shallow depressions, and to the outside of the lateral ridges are still shallower depressions. These lateral ridges represent those that have been described in the two previous vertebrae as converging like the arms of a Y to meet a median ridge which was likened to the stalk. (See H in pl. XXV., fig. 10, and in pl. XXVI., fig. 3). In the present vertebra, however, the arms, instead of meeting, subside independently upon the neural platform.

The fore-and-aft length of the neural roof is to that of the floor as 42 mm. is to 65 mm; thus there is relatively less of the floor exposed than in "A" and " B." The distance from the summit of the neural spine to the mid-point of the preaxial edge of the neural roof is one-third greater than from the spine to the corresponding point in the postaxial edge, the figures being as 30 mm. is to 19 mm.

An interzygapophysial bar defining a corresponding foramen is present, but in a dislocated condition, on the right side, while on the left the two broken piers of it only remain (figs. 3 and 5, E).

POSTERIOR CERVICAL VERTEBRA (C).Pl. XXVII.

This vertebra, from its characters and fit, is judged to have immediately preceded "D," which was that last described as the middle member of a supposed series of three consecutive elements, and its features may be sufficiently indicated by comparison with "D," from which it differs only slightly and in serial degree. Compared with this vertebra, the body is slightly longer, and both the front and hind articular surfaces slightly smaller in each of the principal axes. Both prezygapophyses are wanting, but the posterior are less elevated above the neural platform, rather less widely separated and bear smaller articular facets. The top of the neural spine (figs. 1-3, N), slightly less prominent than in “D," forms a low, but distinct, projection with similar relations to the zygapophyses, as described for the previously described vertebra.

The two ridges then mentioned as continued, preaxiad, from the front ends of the front zygapophyses (pl. XXVII., fig. 3, S, S) are present here also. Converging in their descent they meet a little behind the margin of the neural roof, but from their point of meeting no median ridge is continued forwards as in “A." The low median ridge (0 in fig. 3, pl. XXVIII), which in "D" ascends upon the preaxial face of the neural spine, is not here evident.On the ventral surface of the centrum the catapophysis of the right side (fig. 4, R, to

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the observer's left) has remained intact; while that belonging to the right side is somewhat damaged; the uninjured process forms a pre-postaxial ridge springing from a slight intumescence which belongs rather to the under surface of the centrum proper than to its parapophysial extension. The free edge of the ridge is directed rather more mesiad towards its fellow than ventrad, and the interval between the two is about equal to what would have obtained in "D." had these processes been present in that vertebra. The catapophyses generally of these vertebrae, though not very prominent processes, seem particularly liable to be broken, and this is the earliest vertebra in which even one of them has' remained quite intact.

The contour of the neural canal is here almost a perfect circle, and the length of the neural roof is to that of the neural floor as 41 mm. is to 61 mm.

In other respects than those mentioned, so far as the parts are present, the description of "D" may apply to this vertebra also.

POSTERIOR CERVICAL VERTEBRA (E).Pl. XXIX.

This segment is considered to have directly followed" D," and may, as in the case of "C” be described by comparison with that vertebra.

In its main features it shows a progressive increase in those variations by which" D" differs from" c." Thus the body is shorter, and its pre- and postaxial articular surfaces rather larger, than in "D," though their general characters are similar; one prezygapophysis (pl. XXIX., fig. 3, AZ) only is present which presents much the same characters as in "D." The postzygapophyses (pl. XXIX., figs. 1, 2, 3, 5, p) show a further increase in elevation and in the interval between them. They are also shorter in a fore-and-aft direction than in either "C" or "D." The neural spine (figs. 1, 2, 3, N) is slightly more prominent and elevated, and the length of the slope from the preaxial edge of the neural roof to its summit is also considerably in excess of what it is in the segment with which it is compared. The effect of this lengthened preaxial slope is to throw the summit of the neural spine further back and therefore considerably nearer to the postaxial neural margin than.it is in "D," with the result that the posterior interzygapophysial fossa is less extensive in a fore-and-aft direction. Nevertheless the total length of the neural roof and its proportion to the neural floor remains about the same. The catapophyses, of which one is in a fairly perfect condition, are closer together than in the antecedent vertebra. The neural canal is a full ellipse with the longer axis transverse, and is of approximately of the same size as in "D." In other respects the description of that vertebra will apply to this segment also.

CERVICO-DORSAL VERTEBRA (F).Pl. XXX.

This segment, notwithstanding its greatly damaged condition, reveals a continuance of those serially progressive changes that have been noticed in the preceding vertebrae,

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and also introduces new features from its having been the bearer of a movable rib. We consider it to have been an early member of the cervico-dorsal series.

Its centrum is slightly shorter (6 mm.) than that of "E," but its front articular surface is of about the same transverse width and rather broader dorso-ventrally. The dorsal border, when the preaxial surface is viewed directly from the front, gives a contour which is, on an enlarged scale, similar to the corresponding part of "A" in that its median part only is concave, while on each side of the concavity this margin presents convexities. The ventral border forms, throughout its whole length, a broad, even curve with the concavity directed preaxiad and its curvature lying, if the vertebra be laid with its ventral surface on the table, in a horizontal plane. Moreover, as the points in the ventral border lie postaxiad of the corresponding points of the dorsal margin, the whole preaxial surface has a certain amount of slope postaxiad. Thus, when the bone is viewed directly from its ventral aspect, a considerable part of the preaxial surface is exposed (see pl. XXX., fig. 4, AA). In the segment last described (E) scarcely any part of this surface comes into view in a similar position (cf pl. XXIX., fig. 4), but in the present vertebra the extent of its exposure is a conspicuous feature, two-thirds, at least, of its extent being visible under these conditions.

In the posterior articular surface (fig. 2, B) the dorsal border is concave; the ventral, but for some damage, would have appeared very slightly convex, and also to have been produced into a sharp lip reaching distinctly postaxiad of the dorsal border. The transverse diameter of this articular surface at its dorsal margin is rather less than that of the ventral and about equal to the dorsa-ventral height measured in the mid-line. Compared with the corresponding face of "E,” the principal change in the posterior surface is the increase of dorso-ventral height relatively to the breadth.

The ventral surface of the centrum (fig. 4, V) presents, in front, the wide concavity formed by the corresponding border of the front articular surface, and, as has been stated, a large portion of this articular surface is exposed when the bone is viewed from this aspect. The posterior border of the body, coincident with the ventral border of the hinder articular surface, is convex to the extent of forming almost a semicircle. In advance of this the lateral borders form concavities, more marked than in any of the vertebra: previously described and, then, they become considerably divergent till they meet the parapophysial rib facets (figs. 4 and 5, X). A little in advance of the region of greatest constriction of the ventral surface are paired, low ridge-1ike cat apophyses (fig. 4, R, R) here situated well on the actual, ventral surface of the body and approximating to one another still more closely than they did in "E." Behind the catapophyses the ventral surface of the centrum is convex, transversely, this feature being in contrast to the shallow median groove which marks this region in antecedent vertebra:. The catapophyses naturally define a furrow between them, the floor of which slopes considerably dorsad as it advances preaxiad until it meets a wide transverse groove extending nearly the whole width of the centrum and of which the front limit is the ventral border of the pre-

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axial articular surface. Close to the latter border is an irregular row of small vascular foramina (fig. 4). The lateral extensions of the transverse groove become narrower and shallower, and run out just before reaching the lateral borders of the body behind the parapophysial facets.

On the lateral surface of the centrum, and within the preaxial-ventral angle is a subreniform, nearly flat, facet for the head of a rib (figs. 4 and 5, X), which faces chiefly externally but also somewhat ventrad. Extending postaxiad from this rib facet to a little outside of the hypapophysis is a strongly marked ridge which delimits the lateral and ventral surfaces of the centrum and contributes by its presence to the depth of a circumscribed indentation of about the size of the top of a little finger which lies just dorsad of it (see fig. 5 above and to the right of x). The remainder of the lateral surface is, generally though to a slight degree, depressed.

The diapophyses (fig. 3, L) have been lost and the fractured surface reveals on each side a large air cavity in the interval between the fore and hind zygapophyses (shown in fig. 3, above L).

The prezygapophyses are also absent and so also are the greater part of both postzygapophyses. The summit of the neural spine, with which, as in previous vertebrae, the sides of the zygapophyses are coalesced, forms a low rounded rising (figs. 2 and 3, N, where, however, it is not very distinctly shown) between the broken base of the former processes; this is less prominent than in "E," but reaches a slightly greater vertical elevation and has a steeper anterior slope.

The two lateral ridges (fig. 3, 5,5) running preaxiad from the postzygapophyses are here repeated with rather greater prominence than previously, and, as in the more recently described vertebrae, they run out on the neural platform without meeting. Between these lateral ridges there is an indistinct median ridge which is however only faintly and for a short distance expressed in the lower part of the steep slope representing the front surface of the neural spine.

The dimensions and form of the post-interzygapophysial fossa cannot be wholly stated on account of the loss of the greater part of these processes, but enough remains to show that it was shallower pre- and postaxially than in "E;" the posterior surface of the neural spine, which bounds the fossa in front, appears as a barely appreciable low dorso-ventrally striated ridge.

The spinal canal proper to this segment presents some features met with for the first time. Its size is larger than in any vertebra yet described and, in section, it is a full ellipse with the longer axis vertical. The hinder aperture of this segment of the canal is markedly infundibuliform, its dimensions at the mouth being twice as great as at the middle, while still preserving there, on an enlarged scale, the ellipsoidal characters of the more constricted portion of the canal. As one result of this infundibuliform opening, the posterior edge of the roof of the canal stands high above the edge of the neural floor, and the distance between these two points is just twice as great as it is in "E." The

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pedicles in consequence appear high by comparison and their posterior borders are markedly concave.

The anterior opening of the spinal canal is also, to a slight extent, infundibuliform in comparison with the corresponding part of the vertebrae previously considered, and, in as much as the neural platform begins to ascend almost from its anterior edges, the thickness of its substance is also greater than in previous vertebrae. The length of the neural roof to that of the neural floor is as 4:6 mm. is to 60 mm.

CERVICO-DORSAL VERTEBRA (G).Pl. XXXI.

This vertebra has many features in common with" F," together with some progressive modifications which suggest that it may follow that segment in the series, and, indeed, the fit of the two bones in that position, as well as their texture, support the assumption. Like the preceding vertebra, it is considerably damaged, having lost the whole of both prezygapophyses, as well as parts of the margin of the ant articular surface, including the rib facets. Fortunately one uninjured postzygapophysis remains. Comparing this vertebra with "F," the length of the body is about the same, but the antarticular surface has its dorsal border, only very slightly concave instead of being, as in "F," rather deeply indented in its mid-region. The comparison between the transverse breadth of the surface in the two vertebrae cannot be accurately made owing to damage in this, but it was apparently rather less in the present than in the segment believed to precede it, while the dorso-ventral depth is, here, rather greater; there is, moreover, a similar retrocession of the surface as it extends ventrad; thus, as in the last vertebra described, when the bone is viewed from the ventral aspect, nearly the whole of the articular surface is exposed.

A portion of the post articular surface has been damaged and restored, but it would appear to have been very similar in form and dimensions to this part in "F." The ventral surface of the body displays the same general features as in "F," the principal difference being in the paired hypapophyses (fig. 4, R.R.). These are less prominent than in that vertebra, being, indeed, of very slight elevation; they are also shorter prepostaxially and considerably closer together.* It is, in fact, principally because of the closer approximation of these· two processes that suppose that this segment succeeds that previously described.

Behind the hypapophyses the ventral surface of the body is flat pre-postaxially and convex transversely, though, in this latter direction, the degree of convexity is rather less than in "F." The transverse groove in front of the parial processes is not so wide, though it is as deep, as in "F." On the lateral surface fracture at both antero-ventral angles has removed the parapophysial rib facets.

Both prezygapophyses have been, as stated, completely lost, but the single postzy-

* Owing to their slight elevation they are hardly evident in Fig. 4.

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gapophysis (figs. 2, 3 and 5 P.) that remains has about the same dimensions as in "E" -the last vertebra described in which a posterior zygapophyses was present, though it rises slightly higher than in that segment. Its articular facet is subreniform, very gently convex antero-posteriorly, and flat transversely. It faces, as in "E," to about an equal degree ventrad and externad. Surmounting it is a broad-based, rather rough and low hyperapophysis, on which the latter P in fig. 3 is placed. On the outside of the zygapophysis a broken bony prominence occupies the position of the hinder pier of the bridge of bone described in "A " as closing an interzygapophysial canal (fig. 3, E).

The substance of the neural platform, succeeding, postaxially, the preaxial edge of the neural roof, is less thick than in "F," and is nearly flat for the distance of about half an inch before the steep ascent of the front face of the neural spine begins.

From this point the front aspect of the neural spine (figs. 1,2,3 N), with which, as in preceding cases, the postzygapophyses have coalesced, ascends with an incline steeper than in "F," but reaches to about the same height. The summit of the spine does not, however, here, stand out as a distinct projection, but from its highest level rise the antero-internal faces of the postyzgapophyses. The fossa (fig. 3, F) between these is of about the same antero-posterior depth as in "F," and the postaxial margin of its floor, which is, at the same time, the roof of the neural canal, reaches rather beyond (postaxiad) the corresponding lip of the floor of the canal.

The two converging ridges (fig. 3, S S), which have been described in previous vertebrae as extending, preaxially, from the front ends of the postzygapophyses on to the neural platform, are, in this segment, somewhat asymmetrical-that on the right side being the more prominent, and, owing to the fact that the declivity of the ridges is less steep than that of the actual front surface of the neural spine, the former stand out in relief from the latter. The effect of this is to give an appearance of depression to the region between them. The median ridge, indicating the preaxial surface of the neural spine, is here represented by an ill-defined low, and vertically striated, rising; it, like the lateral ridges, also runs out before reaching the edge of the neural platform.

The section of the neural canal is rotund-oviform with the broad end dorsal; its posterior outlet is infundibuliform in much the same way as in "F," and, at the preaxial end, there is considerable divergence of the lateral walls, though not of the roof and floor.

The lateral surface shows, to the right of D, in fig. 5, the opening of a pneumatic foramen.

CERVICO-DORSAL (OR DORSAL VERTEBRA (H.).Pl. XXXII., figs. 1-4.

As this fragment has lost the whole of its epaxial parts, the determination of its position depends almost entirely upon the characters of the hypapophysis, and it may, therefore, be advisable, as a preliminary, to review the arrangement of these processes in some other members of the Ratitæ.

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The parial haemal processes for which we have used the term catapophyses make their appearance in the vertebral column of those Ratitæ, which are available to us with remarkable constancy at about the fifth or sixth cervical vertebra.*

As more postaxially situated segments are reached, these twin catapophyses (on the whole, but not always uniformly) approximate towards one another, and, in so doing, shift their position from the under surfaces of the parapophysial constituents of the lateral arches, on which they are at first situated, to the ventral surface of the centrum itself. This gradual approximation ends in coalescence, but the coalescence is at first not quite complete.

In the Emeu a transitional condition of incomplete coalescence occurs on the nineteenth or first cervico-dorsal vertebra. In this, while the distal, and greater, portions of the two processes are separate, these spring from a common base, which is broad, slightly raised, and situated entirely on the ventral surface of the centrum itself. In the succeeding or twentieth vertebra the hypapophysis is single, median, and deeply carinate.

In the Cassowary the catapophyses are double on the eighteenth, or second cervico-dorsal, vertebra; these, on the next segment, have combined into a single process with a broad base and bifid extremity. On the twentieth vertebra is a single hypapophysis of a compressed carinate character.

In the Ostrich, proceeding postaxiad, the last vertebra on which the processes are double is (in the particular specimen under observation) the seventeenth. The eighteenth, or ultimate cervico-dorsal, segment has a single process with its ventral extremity laterally expanded and bifid, and of a form generally similar to the haermapophysis of the nineteenth vertebra in the Cassowary. Slight indication of the bifid character is retained on the succeeding or nineteenth segment, and is not wholly absent on the twentieth.

In Rhea the transition is from twin processes on the fourteenth, or last cervico-dorsal, to a ventrally elongated, laterally compressed and pre axially directed single median process. In the Dinornithidæ the catapophyses, which, as previously mentioned, appear on the 6th segment, "increase in size in each posterior vertebra, and are widest apart at No. 15 or 16. They then approach and coalesce into a median tubercle on No. 19 or 20." t

In Apteryx bulleri there is a sudden transition from well marked parial processes on the 11th vertebra: to a single and prominent median process on the 12th, a statement which is in accord with that given by Mivart.

* In the skeletons used for comparison we find them making their appearance as follows:-In Dromœus, at the 6th vertebra; Casuarius galeatus, 5th; Struthio camelus, 5th; Rhea americana, 5th; Apteryx bulleri, 6th. As regards the Dinornithidae, our only available skeleton with the vertebral numerically complete being a composite, we take Captain Hutton's statement that "a pair of hypapophyses spring from the ventral surface of the parapophyses in No. 6 ("Axial Skeleton in the Dinornithidae;" Trans. and Proc. New Zealand Institute, vol. XXVII., 1894, p. 159). In Apteryx bulleri our skeleton shows the paired processes to be first apparent on the 6th vertebra, though Mivart states that the 5th is the first to show them ("Axial Skeleton of the Struthionidae ;" Trans. Zool. Soc., vol. X., p. 35).

t Hutton, loco cit.

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The twin hypapophyses haying completely coalesced into, or become replaced by, a single median process the latter persists, with, on the whole, diminishing size and thickness and with certain other variations, up to the twenty-second vertebra in the Emeu, the twenty-first in the Cassowary, the twenty-second in the Ostrich, the eighteenth in Rhea, and the nineteenth in Apteryx bulleri, on which last, however, it has the form of a very low keel.

In the subsequent free prepelvic vertebra: of the birds just mentioned, the hypapophysis becomes reduced either to a low median ridge, which becomes less and less salient, or which may only be evident along part of the length of the ventral surface: or the ridge may be represented by insignificant preaxial or postaxial tubercles or low spines. In the last prepelvic vertebral segment, or last but one, all traces of the hypapophysis have usually disappeared.

To return, in the light of this review, to the vertebra (H) under description.Its anterior articular surface (pl. XXX II., fig. 1, A), rather narrower transversely but

slightly wider vertically, than in the vertebra last described, is more deeply concave than in any segment yet examined, its contour forming little short of a semicircle. In the dorso-ventral direction the surface is very slightly convex. The dorsal border is slightly concave, and the ventral, to an equal degree, convex, the two curves being thus almost concentric, though, measured along the curves, the length of the latter exceeds that of the former. Of the postarticular surface (fig. 2, B) the dorsal margin has been slightly damaged, but, in the intact condition, it would appear to have been slightly concave. The ventral border is strongly convex, and its contour, if taken continuously with the ventral halves of the lateral borders, forms an uninterrupted semicircular sweep. The dorsal halves of the lateral borders are somewhat drawn in towards one another, so that the transverse width of the articular surface becomes here reduced. The dorso-ventral height of this surface exceeds the lateral width at its narrowest, but is less than that of the widest part.

The floor of the spinal canal, which is all that remains of it, is longitudinally very gently convex along its length.

The disposition of the hypapophysis (figs. 1-4, R), from its close incorporation with the centrum, is not easy of verbal description, but, if we regard as properly belonging to the process all that part of the bone which lies ventrad of a fore-and-aft plane meeting the ventral borders of the pre- and postarticular surfaces-all, in fact, which lies below the dotted line in fig. 4-we may then, perhaps, liken the hypapophysis to a wedge with one flat, and one transversely convex, side. The flat side of the wedge corresponds to the plane of attachment of the hypapophysis to the centrum as indicated by the dotted line, and, of course, has no existence as a separate surface. The convex side forms the ventral surface of the hypapophysis, and this must further be regarded as cc pinched" in at the middle. Under this description the edge of this plano-convex wedge corresponds to the median portion of the ventral edge of the antarticular surface.

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Continuing the above simile, we must then consider the ventro-lateral angles of the head of the wedge as produced into two subconical, divergent processes (only one of which is intact) directed preaxiad and outwards. These processes project a little preaxiad of the ventral border of the antarticular surface. They are shown, from a ventral point of view, in fig. 3, and one of them appears in profile in fig. 4 R.

Regarding the hypapophysis from another point of view, it might be described, with less detail, as a broad, median, sub-bifid process springing from the ventral and forepart of the body; the ventro-lateral angles of the process being produced into two divergent bluntly conical processes.

If we are to regard as belonging to the hypapophysis all that, in front, lies ventral to the lower border of the antarticular surface, the process has its greatest dorso-ventral depth at its front face, this being here nearly equal to the corresponding dimension of the antarticular surface. From this point of greatest depth the under surface of the hypapophysis pursues, in its mid-longitudinal line, a straight course. till it meets, and becomes coincident with, the ventral edge of the hinder articular surface,

In transverse (dorso-ventral) sections the ventral surface of the hypapophysis would give, proceeding from behind forwards, convex contours up to the region of the divergent processes, but, as before mentioned, its sides are, as it were, "pinched in " at about the middle, so that when the vertebra on a whole is viewed ventrally, the body shows a considerable amount of an hour-glass constriction; this feature is shown in fig. 3.

Viewed laterally, the only important characters left for notice are the parapophysial rib facets (fig. 4, X) which are small, not very well defined, though somewhat elevated, and situated a little distance within the angle formed by the preaxial and ventral margins of the horns which enclose the antarticular surface.

In the general plan of the hypapophysis, considered in the light of its serial modifications in other Ratitae, this vertebra is most nearly paralleled by the conditions existing in the 19th vertebra of the Cassowary and in the 18th of Struthio, these being in each case the last of the cervical series.

In the Emeu there is, in this respect, no equally comparable segment though, in this bird, it is the hypapophysis of the 19th or first cervico-dorsal which makes the nearest approach to that of the fossil vertebra.

CERVICO-DORSAL (OR DORSAL) VERTEBRA (I.).Pl. XXXIII., figs. 1-4 and pl. XXXIV., fig. 1.

It is particularly unfortunate that the last vertebra described (H) retained none of the structures dorsal to the floor of the neural canal for, had these been present, they might have yielded transitional modifications which would have led up to, and enabled us to explain better, the conditions found in the epaxial parts of the vertebra now to be

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described. It is equally unfortunate that these parts are unrepresented in any of our vertebral fragments which come later in the series than the one under consideration. Thus we lack the guiding of both antecedent and subsequent structural modifications in these parts.

Moreover, some of the features found in this remarkable vertebra are not to be found, or, at least, not to an equal degree in any other avian vertebra to which we have access.

Nevertheless we are not altogether without some anatomical leading, for, as we hope to show, the same plan of structure is to be found elsewhere, and it is rather by reason of the extreme degree to which certain modifications have reached than of the introduction of strictly novel features that the vertebra is remarkable.

Passing to its description, it has lost nearly the whole of the right half of the antarticular surface and of the left transverse process with its prezygapophysis; fortunately, these parts, which are absent on one side, are present in good condition on the other, so that exact data exist for complete reconstruction. Describing the preaxial articular surface (pl. XXXIII., fig. 1, A) as if it were complete, its transverse width exceeds, but not greatly, that of the homologous surface of "H," and this dimension is about twice that of the dorso-ventral height in the mid-line. The degree of concavity (transversely) is considerable, this feature being contributed to by a slight inflexion, mesiad, of its lateral horns. Dorso-ventrally the surface is very gently convex, and there is only a very slight degree of that retrogression of the surface, as it descends ventrad, that was noticed in the case of "F," and, to a still greater degree in "G." The dorsal border is slightly concave; of the ventral, the two lateral halves are gently sigmoid, forming where they meet in the middle line a ventrally directed point.

The hinder articular surface (pl. XXXIII., fig. 2, and pl. XXXIV., fig. 1, B) is subquadrate and markedly saddle-shaped, the dorso-ventral height being about equal to the narrowest transverse diameter. In size and shape it approximates to that of the corresponding surface in "F." The dorsal border is concave; the ventral more gently convex, though the curvature of the latter becomes augmented in the ventro-lateral regions where it sweeps round to form the lateral borders. These are concave in their dorsal third, ventrad of this they are convex, and not very sharply defined from the lateral surfaces of the centrum.

The ventral surface of this vertebra (fig. 4) we may perhaps best describe by likening it to the seat of an inverted saddle with a very broad pummel, to which, indeed, it bears a close resemblance in its conformation. Under this simile the cantle of the saddle stands for the broad and rounded hinder border of the surface, and the seat for the broad part in front of this border, on which the letter V stands in fig. 4; the transverse width of the bone then narrowing as it advances gradually rises into an elevation that has been likened to a pummel, * and which, in fact, represents a broad single median hypapophysis.

* The application of this comparison, of course, requires that the bone should be

considered as placed with its ventral surface uppermost.

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Further, the preaxial (and actual) ventral surface of the hypapophysis is, as it were, "pinched up" into a low median longitudinal ridge (see fig. 4 in front of V) which subsides at a point where, following our simile, the pummel merges into the seat. The preaxial end of this ridge bifurcates into two obscurely marked divergent risings which terminate on each side in low, obtuse elevations.

Viewed preaxially, with the ventral surface downward, the hypapophysis (pl. XXXIII., fig. 1, R) may be described in much the same way as in "H" as a broad median process of rather greater width than height, and springing from the fore part of the centrum, a very little behind the ventral margin of the antarticular surface, by a base of attachment which is narrower, transversely, than the more ventrally situated portion of the hypapophysis. From this (preaxial) point of view the low median ridge appears with its preaxial bifurcation upon the front face of the hypapophysis. This face of the hypapophysis (pl. XXXIII., fig 1, R), comprising the area which lies between the angle enclosed by the bifurcation and the ventral edge of the prearticular surface, is nearly flat.

The only salient feature of the lateral surface of the centrum of this vertebra (pl. XXXIV., fig. 1) is the parapophysial rib facet which is present only on the left side, and, consequently, not shown in the figure in which the right side is represented; it is small and considerably raised on a pyramidally shaped eminence indicated by X in figs. 1, 2, and 4. The facet lies in each case just external to the letter.

The prezyapophysis (figs. 1 and 3, AZ) present on the right side only, is large, being fully twice the size of that in "E "-the last vertebra described in which this part was represented; it is subpyriform, with the larger end anterior, very slightly concave transversely, almost flat antero-posteriorly, and facing to an equal extent mesiad and dorsad. From its outer aspect projects a very large and massive transverse process or diapophysis (L in all the figures) which has, at the same time, a slight inclination ventrad.

On the upper surface of the diapophysis, mid-way between its outer extremity and the edge of the prezygapophysis, is a well-marked ridge which apparently represents a metapophysis, the position of which is indicated by the letter L in figs. 1 and 3 of pl. XXXIII. Between this ridge and the outer edge of the diapophysis are two smaller and less prominent parallel ridges.

On the outer apex of the diapophysis is a small, and not very pronounced, flat facet or the tubercle of the rib (pl. XXXIV., fig. 1, Y, and just external to Y in fig. 2 of the previous plate). Projecting from the hinder part of the upper surface is what appears to be a broken anterior pier of the interzygapophysial bar (pl. XXXIII., fig. 1, E), and on the under surface is the large opening of a pneumatic foramen (shown in fig. 4 to the right of L). From about the middle of the mesial·border of the prezygapophysial articular facet proceeds, mesiad and postaxiad, the prominent, thick, and rounded preaxial edge of the neural platform (pl. XXXIII., fig. 1, T) to nearly the middle of its course, where it is interrupted by fracture. Midway between this fractured edge and the posterior

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border of the neck of the transverse process is another large pneumatic orifice, shown in fig. 1, pl. XXXIII., to the right of, and above, the prezygapophysis. The length of the body measured from the mid point of the anterior and posterior articular surfaces is·51 mm.

In respect to the configuration of the neural spine and postzygapophyses this vertebra presents a great contrast to all antecedent segments with which comparison is possible. The latter processes, together with the neural spine with which they are coalesced, form a large pyramidal mass cleft at the summit and deeply excavated behind (pl. XXXIII., figs. 1 and 2). At first appearance the ensemble suggests a massive bifid spine. Its true composition, however, is explained in the light of certain modifications that have been met with in previous vertebra, and that exist in those of other ratitite birds.

Referring to the description of vertebra "A," the view was taken that the neural spine is represented by the low bony bar joining the anterior ends of the postzygapophyses. In subsequent vertebra: the height of this bar increases and its dorsal surface, moreover, rises into a distinct, if low, conical prominence clearly suggesting at this stage the summit of a spinous process with the sides of which the inner surfaces of the postzygapophyses have coalesced. In the vertebra: previously described, however, the form and upper surfaces of the postzygapophyses have not materially altered up to "G " except in so far as they have become progressively shorter, broader and more widely separated. In "H " the processes in question were absent, but in the vertebra now under description, besides a further shortening in their pre- and postaxial length, their dorsal surfaces have become elevated into stout and high buttresses which are not only applied to, and coalesced with, the whole vertical length of the neural spine, but considerably overtop the latter (see pl. XXXIII., figs. 1,2,3, and pl. XXXIV., fig. 1, P). It is, in fact, the summits of these two buttress-like elevations from the postzygapophyses which confer on the whole composite bony mass the bifid character that has been noticed, and not the bifurcation of the actual spine itself.

Between the summits of these buttresses is a well-defined valley a little in front of which the preaxial, dorsal angle of the spine forms a salient projection (pl. XXXIII., figs. 1 and 3, and pl. XXXIV., fig. 1, N); below this a rugose tract stands in low relief from the general front surface of the pyramidal mass as it descends steeply to the neural roof.

Viewed from behind the prominent posterior borders of the buttresses (pl. XXXIII., fig. 2, P P) converge towards their summits, diminishing, in transverse thickness, from their bases upwards for about two-thirds of their height, from which point the thickness increases slightly for the rest of their elevation. Their inner surfaces are the lateral boundaries of a deep interzygapophysial fossa of which the front wall is the. vertically striated hinder surface of the neural spine and the floor the, here, vertically thick roof of the neural canal. Two inconspicuous elevations just lateral to the hinder border may represent hyperapophyses; their position is indicated by the letters P P in fig. 3 of pl.

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XXXIII. The section of the neural canal is nearly circular, inclining towards a very full, transversely extended, ellipse; its anterior outlet, being for its greater part damaged, does not admit of exact description.

At the hinder aperture of the canal the floor is for the most part on an even fore-and aft level,·though for a slight distance from its end, it inclines a little ventrad. The roof, from about the middle of the canal, inclines rapidly, dorsad, in its course postaxiad, with the result that the postaxial edge of the roof stands very high above the level of the floor; the elevation is, in fact, as great as the maximum vertical height of the postarticular surface, and is almost equal to the height of the zygapophysial buttresses above the neural roof. These features are shown in pl. XXXIII., fig. 2. The lateral sides, also, of the hinder aperture of the neural canal are slightly divergent postaxially, so that the combined effect of these inclinations is to confer, to a much greater extent even than in "F" and “G" an infundibuliform character on the posterior outlet of the canal.

Using the hypapophysis of this segment as the principal guide, we consider its position to be that next after “H" in a larger bird. In that vertebra the hypapophysis represents the condition that has been mentioned in which the parial haemal processes have partially, but not entirely, coalesced, as indicated by the bifid character of its preaxial extremity, and this condition is also exemplified in the Emeu, Cassowary and Ostrich.

In the fossil segment under consideration the hypapophysis represents a condition in which the fusion of the catapophyses is complete, though, instead of having the laterally compressed, or deeply carinate, form that obtains on complete coalescence in the living forms mentioned, it is depressed, broad~ and generally rounded.

Before leaving this vertebra, we may make a few further remarks on the postzygapophysial buttresses that form so conspicuous a feature in its conformation, in the light of comparison with those of other ratitite birds, particularly in the case of the Cassowary.

These buttresses, to use the appropriate word employed by Lydekker,* appear to be massive developments of two ridges which are continued, divergently backwards, from the neural spine (or spines when this is double) on to the dorsal surface of the postzygapophyses, where they coalesce with the hyperapophyses. To these Huttont applies the term neural ridges, and Lydekker speaks of them as postzygapophysial ridges.tt Among the ratitite birds of which we have complete and natural skeletons for comparison, the spinal column of the Cassowary offers the nearest approach, in respect of these buttresses, to the conditions found in Genyornis, and it may be well, therefore, to follow up their serial modifications in this existing bird.

*Brit. Mus. Cat. Of Fossil Birds, p. 342t The Axial Skeleton in the Dinornithidae (Trans. New Zealand Inst; vol XXVII., 1894, pp. 159-160)tt Quoted by Hutton, ibid

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In the seventh cervical vertebra of the Cassowary (C. galeatus) the top of what we regard as the proper neural spine is a short low antero-posterior linear ridge. From the hinder end of this two well-defined, divergent ridges, themselves also linear in character, are continued on the dorsal surface of the postzygapophyses until they meet the hyperapophyses, which are here quite distinct. These are the neural ridges of Hutton.

From the seventh vertebra up to the twelfth the neural ridges become more prominent, and increasingly divergent and rugose, the hyperapophyses also sharing in the increment of size. The low linear elevation, held to represent the spine, is distinct from the neural ridges on the ninth vertebra, but on the tenth doubtfully so, while, on the eleventh and twelfth, the neural ridges have met and become continuous in the mid-line so as to cover up the spine.

On the thirteenth vertebra the inner or preaxial ends of the neural ridges, which have still further increased in size, elevation and rugosity, have ceased to meet at the midline, though they approach one another closely. Between their inner ends is left a cleft or channel, the ventral part of which is blocked by a bony bridge representing the spine, and this is more or less overhung by the approximated preaxial, or mesial, ends of the neural ridges.

In the next-the fourteenth-much the same condition exist, save that the mesial ends of the ridges are now prominent, and have reached a considerably higher elevation than the hyperapophyses, which latter, nevertheless, preserve their individuality. The bony bar, representing the spine, has also increased in elevation. The fifteenth vertebra is in the respects very similar to its predecessor.

The sixteenth shows a further increase in height, both absolutely and relatively to the hyperapophyses, and the inner ends of the neural ridges have further approximated, and thus overhang to a still greater extent the neural bar.

In the seventeenth the neural ridges are mesially, almost in contact, and rise still higher above the bar while their degree of divergence, which in the three preceding vertebrae has remained pretty constant, is now slightly reduced. On the whole, the conditions of the neural spine and its lateral adjuncts found in the fossil vertebra last described are most nearly approached by those of the sixteenth and seventeenth of Casuarius, though, in the latter, the relative development of the buttresses falls short of what exists in the former.

In the eighteenth segment there is partial contact, mesially, of the neural ridges, but not actual concrescence and these are at the same time reduced in thickness. The bar, representing the spine, has also increased in height to an extent that its summit lies just below the narrow cleft now left between the preaxial ends of the ridges. The divergence of the ridges themselves is also noticeably reduced.

In the nineteenth vertebra the ridges have so considerably increased in height, with coincident reduction of lateral width, that they have become laminar in character, and,

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moreover, what may now be more appropriately termed their dorsal extremities have met and coalesced with one another over, and with, the top of the spine, to the sides of which also they are, as before, synostotically united. The preaxial edge of these flattened buttresses project on each side preaxiad of the face of the actual edge of the spine which lies between them, so that this surface of the spine, roughened for ligamentous attachment, lies, as it were, at the bottom, as it were, of a shallow recess. But, though spine and buttresses are closely united into a single bony structure, the individual constituents can readily be recognised.

The postaxial margins of the laminar buttresses, as did the neural ridges out of which they have grown, are continued, with still diminishing divergence, into the hyperapophyses and form the postaxial, dorsal boundaries of the postzygapophysial fossa. The hyperapophyses, however, having, since about the fifteenth vertebra, undergone gradual diminution of size, are now of insignificant proportions.

On the twentieth vertebra the lateral buttresses are still more laminar in character and are, as in the previous segment, applied to, and united with, the spine, but the top of the latter emerges, dorsally, between them. Moreover, whereas in the nineteenth segment the pre- and postaxial borders of the buttresses incline towards one another as they ascend, so that their shape, as seen from the side, is more or less that of a triangle with a rounded dorsal angle, in the twentieth this inclination is less, and the form, from the same point of view, is consequently more quadrate-a feature which is still more marked on the next vertebra; moreover, in the twentieth vertebra, its preaxial border does not project in advance of the surface of the neural spine to the same degree as in the preceding segment. The hyperapophyses are insignificant, and on subsequent vertebra are nonexistent.

In later segments buttresses and spine have so intimably coalesced that it is no longer easy to distinguish the constituent elements of the, now, laterally compressed " spinous process" of normal form which they together form. With gradually increasing elevation this character is maintained to the twenty-sixth or last free preaxial vertebra. In this last segment, besides its greater length, it is markedly falciform with the apex pointing preaxiad.

DORSAL VERTEBRA (J.).Pl. XXXIV., figs. 2-5.

In this vertebra only the centrum and hypaxial parts are intact, together with the anterior part of the roof of the neural canal. From its excellent fit, color and texture it is not improbable that it immediately follows "I."

The dorsal border of the preaxial surface (pl. XXXIV., fig. 2, A) is concave and the ventral convex, the two curves being nearly concentric, though the former has slightly

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the shorter radius of curvature. Transversely the curve is nearly semicular in extent; dorso-ventrally there is a very slight. degree of convexity, and the width in that direction is about equal to half the length of the chord of its transverse curvature.

The postarticular surface (fig. 3, B) has the same general features as it has in "I," but it is slightly higher, dorso-ventrally, narrower in its transverse width and the ventral border approaches more nearly to a semicircular outline than does that of "I." Moreover, the dorsal border, and to a less degree the ventral, is produced into a prominent lip which accentuates the vertical concavity of the surface.

The ventral surface of the centrum is produced into a stout, laterally compressed and dorso-ventrally extended hypapophysis, the distal extremity of which is considerably expanded laterally in the preaxial region, thus forming, when viewed ventrally, a flat triangular surface with the angles rounded off (see figs. 2-5, R).

The preaxial border of the hypapophysis inclines slightly, but distinctly, preaxiad as it descends ventrad, and the dorso-ventral depth of its preaxial face is equal to that of the antarticular surface in the mid-vertical line.

The postaxial border sweeps, in a gentle curve dorsad and postaxiad, from the hinder end of its flat triangular ventral surface till it meets the ventral border of the hinder articular surface.

The general conformation of the hypapophysis of this vertebra is very similar to that of the twentieth (in some skeletons of the nineteenth) vertebra of the Ostrich, only in the fossil its dorso-ventral depth is relatively greater. To a less degree it resembles that of the twentieth vertebra in the Emeu and Cassowary, though the process in these latter lacks the considerable amount of lateral expansion of the ventral edge that is observable in the fossil.

The lateral surface of the centrum is considerably concave from before backwards, while, dorso-ventrally, it is nearly flat, though the two sides diverge, wedge fashion, from one another as they ascend.

On the outer aspect of the horns that enclose the antarticular surface are the parapophysial rib facets (fig. 4, Y); these are ovo-pyriform, nearly flat, but smaller and less raised than-in" 1."

Postaxiad and somewhat dorsad of this, and opening from a groove in the bone, are two openings of pneumatic foramina leading deeply into the substance of the pedicle and there communicating with one another; these appear in fig. 2 as dark patches to the left of the neural canal. The larger and more dorsally situated of these foramina would, in the intact vertebra, correspond with that described in the last segment as existing ventral to the stem of the diapophysis.

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The section of the neural canal is nearly circular and its floor is nearly straight except for the front half-inch, in which it dips slightly ventrad. Springing from the middle line of the front part of the neural roof is the basal part of the preaxial border of what must have been a considerably compressed neural spine (fig. 3, N).

DORSAL VERTEBRA (K.).Pl. XXXV., figs. 1-4.

This fragment, presenting many features in common with that last described, has sustained almost exactly the same amount of damage in its epaxial parts and, though, in addition, it has lost the hypapophysis, yet the broken surface of attachment of this allows some conclusions to be drawn as to its configuration.

The transverse curvature of the antarticular surface (pl. XXXV., fig. 1, A) has the form and dimensions of a semicircle whose span measured along the chord is slightly less than in the preceding vertebra. The dorsal border of the surface forms a curve of rather less radius than the ventral, and the median region of the latter is produced ventrad in the form of a point which formed the front end of the hypapophysis.

In the postarticular surface (fig. 2, B), though its dorsoventral height is the same as in "J," there is, as compared with this element, a noticeably diminished transverse breadth. The dorsal border is, as in that vertebra, considerably produced postaxiad into a lip.

The broken surface of attachment of the hypapophysis (fig. 3, R) is such as would correspond with a median process more compressed laterally, than in the preceding segment, but no indication exists as to its dorso-ventral depth, the little that remains of the dorsal part of its postaxial contour is, however, very similar to what it is in the preceding vertebra, while it is also probable that the preaxial border reached as far as the ventral edge of the antarticular surface. The lateral surface of the centrum (fig. 4, D) presents no new feature as compared with that of "J" save that the parapophysial facet (fig. 4, X) is nearly twice as large. Of epaxial parts there remains in this fragment rather more of the basal part of the preaxial border of a laterally compressed, median neural spine (fig. 2, N). The anterior face of the pedicle is perforated in exactly the same way as that of·"J." by a lower and smaller, and upper and larger, pneumatic apertures, while, dorsad and mesiad of these, is revealed, on the less damaged side, a third opening which does not communicate, at least by any large passage, with the two former.

In the Emeu, Cassowary, Ostrich and Rhea that vertebra on which complete or imperfect coalescence of the parial hypapophyses into a single median compressed process has taken place, is followed by from two to four others in which these features are maintained. Such hypapophyses distinguish the twentieth, twenty-first, and twenty-second vertebrae of the Emeu and Ostrich, the twentieth and twenty-first of the Cassowary, and the fifteenth to the eighteenth in Rhea americana.

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In each case there is a tendency for the hypapophysis on the last segment of these individual series, whilst preserving its carinate type, to become reduced in lateral thickness, in dorso-ventral depth, or in both respects. In the present hypapophysis its broken surface of attachment (fig. 3, R) gives evidence of a similar reduction in transverse thickness at least. On this ground, together with its excellent fit with "J." and their general similarity in colour and texture, we are fairly confident that "K" succeeds that vertebra both serially and in the same bird, and that their positions correspond either to the end of the cervico-dorsal, or to the beginning of the true dorsal series, if we may use a not very accurate term as designating these vertebrae which bear ribs attached to the sternum.

DORSAL VERTEBRA (L.).Pl. XXXII., figs. 5-8.

In the present fragment, comprising only the centrum with its hypapophysis, the antarticular surface (pl. XXXII., fig. 5, A), though somewhat damaged in its lateral parts to the extent of removing evidence of the existence of rib facets, must have been in its integrity considerably narrower transversely than in any of the preceding vertebrae. The postaxial surface (fig. 7, B) is longer dorso-ventrally than in "K," and considerably narrower, so that it is altogether more elongate in appearance. The dorsal border, especially in its lateral portions, is drawn out into a sharp, and thin, edge and, when the fragment is viewed laterally when held with its long axis horizontal, the ventral lip of the surface projects considerably postaxiad of the dorsal.

The hypapophysis(figs. 5-8, R) is represented by a compressed median, and for the most part sharp edged, keel which begins at the ventral margin of the preaxial articular surface as a rather low, but still, sharp-edged ridge. Gaining in saliency as it runs postaxial it terminates, about half an inch before reaching the ventral border of the postaxial surface, as a laterally compressed prominent process which is, at the same time, thicker in substance than the antecedent ridge. Viewed from the side the ventral edge of the hypapophysis gives an evenly curved contour (see fig. 8, R). From the point of greatest prominence the ridge suddenly subsides with a more rounded posterior border to the ventral margin of the postarticular surface.

In the Emeu, Ostrich and Rhea the last of the vertebrae with a deeply carinate type of hypapophysis is followed by four, and in the Cassowary by five, free prepelvic segments. In the earlier members of these the hypapophysis is represented by a median linear ridge which may have one or other, or both, of its ends augmented into more distinct tubercles or prominences. In the last, or last two, prepelvic vertebrae both ridge and tubercles are generally absent.

Judging the present fragment by the features of its hypapophysis, it corresponds best with the conditions found in the twenty-second of the Cassowary, twenty-third of the Emeu and Ostrich, and the nineteenth of Rhea, though in none of these is the hypapo-

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physial ridge quite so prominent as in the fossil, nor, in any of them, is its posterior part produced in the same way into a compressed point. The fossil seems in fact, to be a segment which represents better than in any of the living species referred to, a transitional form between the deeply carinate and the median-ridged types of hypapophysis. This fragment represents the latest member of the free prepelvic series that we possess.

CAUDAL VERTEBRAE.Pl. XXXV., figs. 5 and 5a-14 and 14a.

A natural series of ten caudal vertebrae were obtained which appear to comprise the whole of this series except the terminal segment. Placed together in normal position, their aggregate length is 127 mm.

In the most proximal of the series the preaxial articular surface (pl. XXXV., fig. 5 A) is oval in contour except in so far that it is deeply emarginate in its dorsal region, where it corresponds with the floor of the neural canal; it is also markedly concave. The postaxial surface is more circular and similarly emarginate, but is flat. These general characteristics of the two surfaces, allowing for their diminishing size, will apply to the later vertebrae of this series. The neural spine (fig. 5 and 5a, N), somewhat damaged on one side, is depressed, and its dorsal part transversely extended into two projecting processes, but its details can better be described in the next segment, where it is uninjured. Both transverse processes (fig. 5 and 5a, L) are broken near their origins, but they would appear to have pointed directly outwards.

The ventral surface of the centrum is very flat in both principal directions, and on the lateral surface on both sides is a large orifice situated just below the origin of the transverse process. A similar orifice, in diminishing size, is present on one or both sides of subsequent vertebrae. The neural canal is small and nearly circular.

In the second caudal segment (figs. 6 and 6a) the neural spine is nearly perfect, and shows distinct evidence of its formation by the concrescence, in the mid line, of two symmetrical halves; it, like the preceding vertebra, is laterally extended, but to a rather greater extent. Its summit is flat, the front border somewhat concave transversely, and the hinder convex to an equal degree. Both transverse processes have been lost, but their outward projection would appear to have been accompanied by some amount of inclination ventrad.

The third (figs. 7 and 7a) is in a less perfect condition than number two, but very similar on a slightly reduced scale.

The fourth (figs. 8 and 8a) consists of centrum only, and the fifth (figs. 9 and 9a) of this element with the addition of part of the neural spine and one transverse process. Neither present any new features.

The sixth (figs. 10 and l0a) is the most perfect of the whole series, lacking only the tip of one transverse process; its spine is extended laterally in the same way as has been

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described, but relatively more so; in fact, the lateral width of the spine amounts to three quarters of the distance between the tips of the transverse processes. The anterior dorsal border is sharply excavated at its middle, the posterior nearly straight. The transverse processes are directed so considerably ventrad that their tips project beyond the level of the ventral border of the centrum. Though their extremities are expanded, they do not show any evidence of differentiation into dia- and parapophysial elements as occurs in some of these vertebrae in the Emeu, Cassowary and Ostrich, and this is also the case in the only other intact transverse process -that of the seventh. The stalk of the process is somewhat dorso-ventrally compressed, especially at the postaxial border which is pinched into more or less of a thin edge. The ventral surface of the centrum is concave antero-posteriorly and convex transversely; two very obscure risings at the hinder part of the surface may possibly represent parial hypapophyses.

Nos. seven and eight are similar to No. six on a reduced scale except that, in the former of these two, the transverse processes project directly outward; in the latter they are broken off, but would appear to have had a similar direction.

In No. nine the transverse processes are only represented by slight roughnesses on the body. The neural spine is transversely extended as previously described.

In the tenth, and last of those present, the centrum is laterally compressed, especially in its hinder part; the transverse extension of the neural spine exists to a slight degree only J and its dorsum is marked by a median ridge. There are no transverse processes. The postaxial surface for the articulation of the missing segment is very small; the neural canal is still present, and not much smaller than in the first of the series.

Comparing the constituents of the fossil caudal series with those of the Emeu, these being less dissimilar than those of the Ostrich, there is not the difference in size that might be expected. Taking the first segment, its total vertical height in the fossil is 33mm., as against 29 mm. in the living species. The height of the spine above the neural floor and the fore-and-aft length of the centrum is actually less in the former. Thus the total length of the whole series of ten is in the Emeu 150 mm., as against 127 mm. for the same number of bones in Genyornis. On the other hand, while the articular surfaces of the former are wider, transversely, than they are high dorso-ventrally, the reverse is the case in the latter. The transverse extension of the neural spine is also, both relatively and absolutely, greater in the fossil.

In the Emeu the transverse process is formed mainly by the diapophysis in the first and second of the series, the parapophysis being represented by low prominences springing from the body just ventral to the origin of the former. In the third segment the transverse process might be described as forking into two divisions of almost equal size, one ascending and the other descending, which represent the two constituent elements, and in the fourth, with the same kind of division, the parapophysial moiety is now the larger. In the fifth it is the latter which almost entirely forms the ventrally-directed transverse

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process, while the diapophysis now consists only of a low prominence situated dorsal to the origin of the former. This predominance of the parapophysial element persists, with increasing diminution of the diapophysial element to the end of the series. In the Cassowary a generally similar arrangement obtains.

In both the Emeu and Cassowary there is usually a large pneumatic orifice above, as well as below, the origin of the transverse process, while in the fossil it is present only ill the latter situation, and sometimes only on one side; it is, besides, of smaller size than in the living forms.

In Genyornis the transverse processes, so far as they are present, do not, as has been mentioned, show any division into these two elements either at their bases or apices.

In the caudal vertebrae of the Ostrich the vertical height of the bones, measured from the ventral surface of the centrum to the top of the spinous process, is considerably greater than in the fossil, as is also the length of the body, so that, in comparison, the bones of· the latter vertebrae appear depressed. The section of the neural canal, nearly. circular in the fossil forms, is, in the Ostrich, a rather narrow vertically elongated ellipse.

EXPLANATION OF PLATE XXV.

Fig. 1. Atlas [x], Genyornis newtoni, preaxial view.Fig 2. lateral.Fig 3. preaxial.Fig 4. postaxial.Fig 5. Dromoeus novaehollandiae preaxial view.Fig 6. Casuarius galeatus, preaxial view.Fig 7. Struthio camelus, preaxial view.Fig 8. Cervical vertebra (A), Genyornis newtoni, preaxial view.Fig 9. postaxial.Fig 10. dorsal.Fig 11. lateral..

LETTER RFERENCE.ATLAS.

A Preaxial articular surface.B Postaxial surface.C Ventral lip of postaxial surface and broken base of hypapophysial spine.D Lateral surface..

VERTEBRAE “A” TO “L” AND CAUDAL VERTEBRAE.A Preaxial articular surface.AZ Prezygapophyses; the letters are in nearly all cases placed on the articular facets.B Postaxial articular surface.C Lateral arch bounding vertebrarterial canal.D Lateral surface of centrum.E Bony bar bounding interzygapophysial foramen; also standing for one of its broken piers.F Floor of interzygapophysial surface.H Median ridge on neural platform.JK Extent of broken surface of parapophysial attachment of the lateral arch.L Diapophysis. or broken diapophysial pier of lateral arch.MM Low ridges in interzygapophysial fossil.N Neural spine.O Median ridge on preaxial slope of neural spine.P Postzygapophysis; the letters are placed on the hyperapophyses.PZ Postzygapophysial articular facets.R Hypapophysis or catapophysis.SS Converging ridges running preaxiad from the postzygapophyses into H.T Preaxial edge of neural platform.V Ventral surface of centrum.X Parapophysial (capitular) rib facet.Y Diapophysial (tubercubar) rib facet.

EXPLANATION OF PLATE XXVI..

Genyornis newtoni..

All the figures are of natural size..

Fig. l. Cervical vertebra (B), preaxial view.Fig. 2. postaxial.Fig. 3. dorsal.Fig. 4. ventral.Fig. 5. lateral.

.FOR LETTER REFERENCES SEE THOSE TO PLATE XXV.

EXPLANATION OF PLATE XXVII..

Genyornis newtoni..

All the figures are of natural size..

Fig. 1. Late cervical vertebra (C), preaxial view.Fig. 2. postaxial.Fig. 3. dorsal.Fig. 4. ventral.Fig. 5. lateral..FOR LETTER REFERENCES SEE THOSE TO PLATE XXV..

EXPLANATION OF PLATE XXVIII..

Genyornis newtoni..

All the figures are of natural size..

Fig. 1. Late Cervical vertebra (D), preaxial view.

Fig.2. postaxial.Fig.3. dorsal.Fig.4. ventral.Fig.5. lateral..FOR LETTER REFERENCES SEE THOSE TO PLATE XXV.

EXPLANATION OF PLATE XXIX..

Genyornis newtoni..

All the figures are of natural size..

Fig. l. vertebra (E), preaxial view.

Fig. 2. postaxial.Fig. 3. dorsal.Fig. 4. ventral.Fig. 5. lateral.

.FOR LETTER REFERENCES SEE THOSE TO PLATE XXV.

EXPLANATION OF PLATE XXX..

Genyornis newtoni..

All the figures are of natural size..

Fig. 1. Cervico-dorsal vertebra (F), preaxial view.Fig. 2. postaxial.Fig. 3. dorsal.Fig. 4. ventral.Fig. 5. lateral.

.FOR LETTER REFERENCES SEE THOSE TO PLATE XXV.

EXPLANATION OF PLATE XXXI..

Genyornis newtoni..

All the figures are of natural size..

Fig. 1. Cervico-dorsal vertebra (G), preaxial view.Fig. 2. postaxial.

Fig. 3. dorsal.Fig. 4. ventral.Fig. 5. lateral.

.FOR LETTER REFERENCES SEE THOSE TO PLATE XXV.

EXPLANATION OF PLATE XXXII..

Genyornis newtoni..

All the figures are of natural size..

Fig. 1. Cervico-dorsal (or dorsal) vertebrae (H), preaxial view.Fig. 2. postaxial.Fig. 3. ventral.Fig. 4. lateral.Fig. 5. Dorsal vertebra (L), preaxial view.Fig. 6. ventral.Fig. 7. postaxial.Fig. 8. lateral.

.FOR LETTER REFERENCES SEE THOSE TO PLATE XXV.

EXPLANATION OF PLATE XXXIII..

Genyornis newtoni..

All the figures are of natural size..

Fig. 1. Cervico-dorsal (or dorsal) vertebra (1), preaxial view.

Fig. 2. postaxial.Fig. 3. dorsal.Fig. 4. ventral.

.The extension of the missing portion is indicated by partly continuous and partly dotted contour lines.

FOR LETTER REFERENCES SEE THOSE TO PLATE XXV..The figures on this plate and fig. 1 of plate XXXIV have been reproduced from drawings; all others are photographs.

EXPLANATION OF PLATE XXXIV..

Genyornis newtoni..

All the figures are of natural size..

Fig. l. Cervico-dorsal (or dorsal) vertebra (I) lateral view.Fig. 2 Dorsal vertebra (J), preaxial view.Fig. 3. postaxial.Fig. 4. lateral.Fig. 5. ventral.

.FOR LETTER REFERENCES SEE THOSE TO PLATE XXV.

.

EXPLANATION OF PLATE XXXV..

Genyornis newtoni..

All the figures are of natural size...Fig. 1. Dorsal vertebra (K), preaxial view.

Fig. 2. postaxial.Fig. 3. ventral.Fig. 4. lateral.Figs. 5-14. Preaxial views of caudal vertebrae in serial order.Figs. 5a-14a. Lateral views of the same series..

FOR LETTER REFERENCES SEE THOSE TO PLATE XXV.