﻿68 



FOSSIL REPTILIA OF THE 



girting the base of the spine in Hylceosaurus is, however, simple, unnotched ; the 

 provision for attachment of the spine, in Omosaurus, betokens a greater power of 

 resistance against displacement. The superior strength of the spine, due to its full 

 elliptical shape in transverse section, suggests its application as a weapon to be wielded 

 for attack rather than as one of a merely defensive palisade of spines. 



Considering the number of vertebrse — dorsal, sacral, caudal — which have been recovered 

 in more or less completeness from the intractable mass of some tons weight, including the 

 rest of the above described recovered parts of the skeleton of the Omosaur, it might 

 reasonably be expected that, had the trunk and tail been defended by dermal spines, as in 

 Scelidosaurus and Hylceosaurus, especially by spines similar in number and arrangement 

 to the dermal ridged scutes in the more Crocodilian Dinosaur of the Lias, more evidences 

 of such appendages to the trunk-skeleton should have been found in the grave of the great 

 Kimmeridgian dragon. 



But we are, now, not limited to the head, the trunk, or the tail in quest of positions 

 of armour afforded by dermal bones to extinct members of the Reptilian class. 



In the great Mantellian Iguanodon, or at least in the male of that species, a pair of 

 spines supported by unsymmetrical conical bony cores were wielded for offensive action by 

 the fore-limbs. 1 The form and proportions of the Iguanodontal carpal spine, especially in 

 its degree of compression, are more like those of the spine in Omosaurus than are any 

 of the dorsal spines in Ilylceosaurus. True, the conical spine-core in Iguanodon is shorter 

 in proportion to its basal breadth than is the problematical spine in Omosaurus. 



It is significant of the nature of this one unsymmetrical osseous spine that the bones 

 of one of the fore limbs, the left, and that limb only, should have been preserved, and in a 

 more complete state than any other part or limb of the present remarkable Dinosaurian 

 framework ; the spine in question lay not far from the radius and carpus. 



Two spines of similar form to that of Omosaurus, but of larger size, were discovered 

 near each other in a pit of Kimmeridge clay at Wootton Bassett, Wiltshire, and 

 formed part of the well-known collection of William Cunnington, Esq., F.G.S., now in 

 the British Museum. Whatever contiguous bones may have been dug out of the same 

 part of the pit were not preserved. These two spines form a pair, and resemble each 

 other as much as would the right and left radius, or the right and left ulna, of the same 

 Dinosaur. They differ from the (carpal ?) spines of Omosaurus in having a sharp edge, 

 which in a transverse section, like that of fig. 3, PI. XXII, would terminate one end of the 

 long diameter of the ellipse. The lethal power of the weapon was augmented by this 

 character of the sword added to that of the pike. The degree of obliquity, the coarse 

 marginal notching, and vascular perforations of the base, are as in Omosaurus ; but the 

 expansion is greater, yielding dimensions of 8 inches and 6^ inches in long and short 

 diameters ; there is a slight submedial ridge dividing the basal articular surface into two 



1 Pal. Monogr., ' Iguanodon,' vol. for 1871, pi. ii, fig. 1, m, r, 



