6 FOSSIL REPTILIA OF THE 



to within a third of its hinder border, which is flat : the whole height of this spine is 

 nine inches, the vertical extent of the entire vertebra being thirteen inches six lines. 

 The spine of the second vertebra, ns, l, has a similar size and shape in the basal third 

 of its extent, but it expands more gradually, especially transversely, and rises to a 

 greater height, continuing to expand in every direction, but especially in the antero- 

 posterior one ; the fore part of its thick extremity being produced so as to overlap the 

 horizontal part of the end of the shorter spine in front. The sides of the thick 

 expanded end of this clavate spine are impressed by irregular decussating ridges, 

 indicative of the attachment of strong tendons or ligaments ; and, from the back part 

 of the side, six inches below the summit, there projects a tuberosity : a less prominent 

 tuberosity forms the border of the overlapping anterior part of the clavate end of the 

 spine. The whole length of the spine is 13 inches 6 lines; the vertical extent of the 

 entire vertebra being 18 inches 6 lines. 



The neural spine of the third vertebra, ns", is somewhat smaller than the foregoing 

 at its most contracted part, three inches above its origin ; but it expands, as it rises, 

 attains a height of 14 inches, and is divided, like the foregoing, into a smooth part, 

 and a summit impressed by the attachments of the nuchal ligaments or tendons. The 

 base of the latter part developes a tuberosity from the fore part and back part of its 

 outer side, and there are indications of ossifications in the interspace between it and 

 the antecedent spine, which seem to have bound them immoveably together. 



The proportions and external configuration of the spines of these anterior dorsal 

 vertebras, the sudden increase of the second spine, the further increase of the third, 

 with the indications of the strength of the muscles or nuchal ligaments to which their 

 expanded tuberculate summits have given attachment, — all recall characters of the 

 spines of the anterior thoracic vertebrae of certain great Mammalia, and much more 

 closely resemble those parts in the tiger or rhinoceros than in the crocodile, the gavial, 

 or in any of the known existing Lizards. But the production of the summit of the 

 second spine, so as to overlap part of that of the first spine, and the partial anchylosis 

 of the second with the third spine, together with the great increase in the thickness of 

 all the spines toward their summit, are characteristics in a great measure peculiar to 

 the present extinct Dinosaurian ; unless, indeed, it participated in them with some other 

 members of the same extinct order of reptiles. 



We cannot view this remarkable configuration of the anterior thoracic vertebras of 

 the Megalosaur without being impressed by an idea of the great strength of the muscles 

 or ligaments — more probably of the energetically contracting muscles — which were 

 implanted in those thick and lofty spines, from which, as from a fixed point, they acted 

 upon the nuchal region of the head. The remarkable fossil, therefore, above described, 

 yields some insight into the vigour with which such a head, consisting chiefly of the 

 well-armed maxillary and mandibular apparatus, must have been made to operate on 

 the bodies which the instincts of the Megalosaurus impelled it to grapple with and 



