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 ofl'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., k, 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 well 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 convex transversely, slightly 

 concave lengthwise; the laminae slightly contract to their union in the spine, 

 which 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. lys ) are twice the length of the posterior ones (/), 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 



