6 
FOSSIL REPTILIA OF THE 
some vertebrae a low and narrow ridge extends from the neur- to the pleur-apophysial 
surfaces, as at c, fig. 4. 
The degree of concavity of the sides of the centrum in the anterior cervicals, 
exposed in the specimen figured in Tab. Ill, fig. 1, has been exaggerated b}^ the pressure 
to which it has been subject, the effects of which are more conspicuous upon the skull ; 
the cancellous mid-part of the centrum has opposed less resistance than the compact 
articular ends. 
The atlas (a) has been disarticulated from the occipital condyle (i) ; the hemispheric 
articular cup is thus well displayed, with its smooth and shining surface. The coales- 
cence of the centrums of the atlas («) and axis (a?) is complete. A tubercle from the 
side of the centrum of the atlas represents the pleurapophysis ; its neural arch is 
broken away ; that of the axis developes a spine similar to and but little smaller than 
that of the third cervical. 
The dimensions of the seven vertebrae here preserved in connection with the skull 
will be seen in Tab. Ill, fig. 1, where they are figured of the natural size. The 
average dimensions of a cervical centrum of the present species, from the middle and 
basal half of the neck, are, as in figs. 4, 5, 6 — 
lu. lines. 
Length 1 4 
Breadth of articular surface ........ 1 6 
Height of middle of ditto ......... 13 
Length of costal pit ...... ... 0 6 
Transverse diameter of outlet of neural canal . . ..06 
Dorsal series . — The transition from the cervical (Tab. I, c) to the dorsal series (ib., d) 
is effected by the usual elevation of the costal surface by gradational steps, continued 
through about five vertebrae, until a single costal surface is presented by a large 
diapophysis from the neural arch. The number of cervical vertebrae so defined in the 
specimen figured in Tab. I is forty-one. In the first dorsal, characterised by the dia- 
pophysial support of the rib (Tab. IV, figs. I and 2, d), the non-articular part of the 
centrum is smoother than in the cervical vertebrae, the ridges or rugae occupying a 
smaller extent near the two ends, where they indicate the attachments of the capsular 
ligaments. The longitudinal concavity between the two ends is uniform and rather 
more than in the cervicals. The venous foramina are wider apart and not divided by 
any special transverse convexity on the under surface of the centrum. A vertical ridge 
leads from the side of the centrum (ib., c) to the under part of the diapophysis (ib., d), 
nearer the hind than the fore end of the centrum. 
The diapophysis is convex and longest superiorly; the fore part is rather hollowed, 
the hind part flattened, and both converge to the ridge forming the shorter under 
surface. The articular surface (^) of an irregular oval form, with the small end down- 
