8 
FOSSIL REPTILIA OF THE 
vertical diameter of its articular end is 2 inches 5 lines ; the surface is moderately 
concave, with the circumference bevelled off convexly; between the two expanded 
ends the centrum is moderately and uniformly concave lengthwise. There is no 
trace of haemal arch in the first caudal. In the second that arch (Tab. VII, fig. 2, h ) 
is articulated to the posterior part of the under surface, and is produced into a 
spine of nearly 4 inches long. In the third caudal (ib., h, c 3 ) and succeeding ones the 
haemal arch has been dislocated, showing its articular surface, which, by mutual 
union of the haemapophysial bases, is single, sub-reniform, transversely extended, 
lightly concave across, and convex from above downward. The haemal canal, 
thus circumscribed, and w'ell shown in the fourth caudal vertebra, is about 2 lines 
in breadth and 1 inch 3 lines in length ; too narrow, it would seem, for the protection 
of the trunks of the blood-vessels supplying so long and so powerful an organ as 
the tail of the Scelidosaurus. This form of the haemal canal or slit has every 
appearance of being natural, and not due to any posthumous compression. 
The haemapophysial surface external to it is conve.x transversely, slightly 
concave lengthwise; the laminae slightly contract to their union in the spine, 
wdiich becomes compressed, and a little expanded from before backwards near 
its termination. The articular surface, after the second haemal arch, is afforded 
in equal proportions by the two conjoined centrums beneath their terminal 
junction. The transverse process of the second caudal (ib., d) arises from 
the anterior two thirds of the vertebra, over the junction of the centrum with the 
neural arch ; a trace of the suture indicating the pleurapophysial character of this 
process is discernible in this and some following caudals. The length of the 
centrum is 2 inches 2 lines ; the fore and aft breadth of the base of the transverse 
process is 1 inch 5 lines; its length is 2 inches 5 lines; its terminal breadth is 10 
lines, ending obtusely. The transverse processes progressively decrease in all 
these dimensions in the following vertebrae. The anterior zygapophyses (Tab. VII, 
fig. l,r ) are twice the length of the posterior ones ( 0 '). by which their extremities 
are overlapped. The fore and aft breadth of the neurapophyses between these 
processes is 1 inch 2 lines ; that of the summit of the neural spine is 1 inch 
6 lines ; the height of the spine from the base of the prezygapophysis is 3 inches 
4 lines. These dimensions are taken from the third caudal vertebra. The five 
consecutive and coarticulated anterior caudal vertebrae in the present block of 
Lias give a collective longitudinal extent of 12 inches. The distal half of the right 
femur (Tab. VII, fig. 2, 65 ), and parts of the right tibia (ib., 66 ) and fibula (ib., 67 ), 
are cemented to the vertebrae by the matrix. Figure 1 in this plate gives a side 
view, fig. 2 an oblique under view, of the first five caudal vertebrae. 
The succeeding (eighth) block includes the five vertebrae (Tab. VIII, fig. 1) 
next in succession. In these the length of the centrum continues to be a little 
over 2 inches, but they gradually decrease in other diameters, and especially in the 
