4 
FOSSIL REPTILIA OF THE 
and of the third cervical vertebra {a, 3) with parts of the pleurapophyses of the 
atlas {pi. a) and axis (pi.x) ; it includes, also, large, massive dermal bones external 
and superior to the vertebral elements. The centrum of the axis is 1 inch 3 lines 
in length, from the line of adhesion of that of the atlas, part of which remains 
connected, as the “odontoid process the proper body of the axis is subcarinate 
below' ; gently concave lengthwise at the sides ; compressed in the same degree at 
the middle, and slightly expanded at the extremities. The rib which it sup- 
ported ipl'a;) is shorter than that of the atlas, but, like it, is slender and straight; 
about 3 inches of the atlantal rib is preserved, and about 2 inches of that of the axis. 
The body of the third vertebra (3) presents a general increase of size ; it is 1 inch 
8 lines in length, 2 inches 3 lines across the parapophyses at the fore part of the 
vertebra, 1 inch 6 lines across the posterior articular surface, and 1 inch 2 lines 
in depth. It is subcompressed at the sides, and more obtusely ridged below than 
the axis. The fore part of the body is articulated by an almost flattened surface 
with that at the back of the axis. 
The characters of the terminal articular surfaces are worked out more completely 
in a consecutive cervical vertebra detached from the third block, and which, from 
its size, is probably the sixth. The part of the front surface (fig. 4, 6) which is pre- 
served, is flat with a convex periphery ; the hind surface (fig. 3, c) is slightly concave, 
with a narrower and better defined circumference. The body of this vertebra is 1 inch 
10 lines in length, 2 inches 3 lines across the parapophyses {p) ; 1 inch 8 lines across 
the hinder articular end (c). The under part of the centrum presents near its fore end 
a hypapophysial tuberosity ; it is constricted at the middle, and a small venous canal 
opens into that concavity on either side. The rib {pti) articulates by a bifurcate 
end with both par- and di- apophyses : the upper transverse process (fig. 4, d) 
extends nearly 1 ^ inch from the neural arch; the neural canal {n) is of a full oval 
form, with the small end downwards ; it is 9 inches in its longest diameter. The 
breadth of the neural arch, below the diapophyses, is 1 inch 7 lines. 
In the portion of the succeeding cervical vertebra, from the same block, the 
rib is directed more outwardly than in the antecedent one. The length of the neck 
of the rib is 1 inch 2 lines; its thickness 6 lines, which increases after the development 
of the tubercle, where the fracture shows a subtriedral section. The portion of the 
articular surface which is preserved {i>) of the centrum of the seventh vertebra 
indicates the same feeble concavity as in the preceding cervical vertebra (fig. 3). 
Supposing the vertebra (Tab. i, figs. 3 and 4) to be the sixth of the cervical series, 
it show's that the rib has more speedily resumed its normal character than in the 
CrocodiUa. In these large existing Saurians the pleurapophysis, slender, straight 
and rather long, in the atlas and axis, becomes shortened and expanded in the 
third, fourth, fifth, and sixth cervical vertebrae, assuming in them a hatchet-like 
shape, with an overlapping arrangement; the posterior production of the “ blade ” 
