288 
DR. MANTELL ON THE OSTEOLOGY OF 
The neural lamina (b) contracts above its base, and again slightly expands ere it 
coalesces with its fellow, the posterior notch as usually being the deepest ; a small 
tract of the body is also, as it were, left uncovered in front and behind to nearly as 
great an extent as in the lumbar vertebrae hitherto assigned to the Cetiosaurus brevis-, 
this character therefore is of no value either generically or specifically. The spine 
{neuracantha) is represented only by a ridge contracting and subsiding towards the 
anterior edge of the neural arch. The strong sub-prismatic upper transverse process 
{d) {plagiapophysts) springs from the upper part of the neural lamina {neuropoma), 
and curves backwards, bending slightly downwards towards its outer extremity, 
which furnishes a large articular rounded surface for the tubercle of the rib. In- 
ternally it is cut away obliquely downwards and inwards for the lodgement of the 
posterior oblique process {met-arthrapophysis) which lies between it and the crown 
of the neural arch, resting on the oval articular facet {f) of the anterior oblique pro- 
cesses (pro-arthrapophysis), which is thus situated on the upper surface of the trans- 
verse process ; those of opposite sides are widely separate, look towards each other, 
and are only inclined slightly towards the horizon, their inner margins being sepa- 
rated by a narrow groove from the sides of the neural laminae. 
The long, thick and compressed peduncles of the posterior oblique processes (g), 
spring from the hinder border of the neural arch on each side of the mesial line, and 
diverge as they pass backwards, projecting much beyond the articular cup of the 
body. Their section is ovate, the lower edge being the thickest ; each is slightly 
twisted on its axis towards the extremity, which is bevelled off obliquely to the upper 
margin for the oval articular surface, looking downwards and slightly outwards. 
We may conjecture that this vertebra is one of the most posterior cervical from 
the high origin of the transverse process, for in the series of five vertebrae behind the 
atlas and axis in the Crocodile, this process rises gradually from the base of the 
neuropome to the middle of its height, and reaches the crown of the neural arch at 
the third dorsal. 
The large vertebra with a wedge-shaped body and convexo-concave articular facets, 
Plate XXVIII. fig. 5, we regard as one of the more anterior of the dorsal region of 
the spine ; in it the inferior transverse process has abandoned the side of the cen- 
trum, and is placed on that of the neural lamina. In the first dorsal of the Croco- 
dile, the perapophysis is still below the neuropomal suture; in the third and fourth, 
the corresponding surface is subdivided by that sutural line ; and in the fifth it quits 
the centrum altogether, but is not placed on the side of the neural arch. No speci- 
men has yet been met with of a dorsal vertebra belonging to the Iguanodon with the 
perapophysial surface or tubercle wholly or partially on the centrum, although that 
character may have been presented by the two or three first dorsal. 
The anterior convexity (a') of the above-mentioned vertebra is much less deve- 
loped than in the cervical, and the concavity behind {a”) is correspondingly shallow. 
The section of the body would present a deep triangular outline with the apex below 
