FOSSIL MAMMALIA. 



87 



verse and spinous processes were exposed to view, as they are represented in 

 Plates XX. and XXIV. The description of these processes has already been 

 given. 



On comparing the cervical vertebras of the Scelidotherium with those of the 

 existing Bruta, the closest resemblance to them was found in the skeleton of the 

 Orycterope. Now this quadruped, though not so rapid a burrower, or so strictly 

 a subterranean species as the Armadillos, participates, nevertheless, to a certain 

 extent, in their fossorial habits, and is closely allied to them in general structure : 

 it differs from them, indeed, mainly in a modification of the dental system, in 

 the absence of dermal armour, and of anchylosis of the cervical vertebras. But 

 the advantages which, as a burrower, it would have derived from the latter struc- 

 ture, are compensated for by the shortness of the cervical vertebrae, and by the 

 great development and imbricated or interlocking co-adaptation of the transverse 

 and anterior spinous processes of the cervical vertebras. The analogous quadru- 

 ped in the South American Continent — the great ant-eater (^myrmecophaga jubata) 

 which uses its powerful compressed fossorial claws for breaking through the hard 

 walls of the habitations of its insect prey, but which does not excavate a subter- 

 raneous retreat for itself, presents the cervical vertebras of a more elongated form, 

 and without that development of the spinous and transverse processes which tend 

 to fix the neck and increase the size of the muscles which move the head : and, if 

 we could conceive that its fore-feet were employed to scratch up vegetable roots, 

 instead of disinterring termites, there would be no reason to expect any modifica- 

 tion of the cervical vertebras as a direct consequence of such a difference in the 

 application of its fossorial extremities : when, therefore, we find that the cervical 

 vertebras do actually differ in two myrmecophagous species, to the extent observ- 

 able in the Cape and South American ant-eaters, we arrive legitimately at the 

 conclusion that such difference relates to fossorial habits of the one species, in 

 which habits the other does not participate. 



Now, therefore, if this conclusion be just in regard to the Orycterope, it must 

 bear with more force upon the question of the habits of the Scelidotherium as the 

 mechanism for strengthening the connection of cervical vertebras, and for aug- 

 menting the surface of attachment of the muscles which worked the head and 

 neck, is more strongly wrought out in that extinct species. 



The great size and strength of the spinous process of the dentata, and the 

 mode in which it is interlocked with the spinous and oblique processes of the third 

 cervical, together with the imbricated disposition of the transverse processes of 

 this and the succeeding vertebras, and the remarkable height of the dorsal spines, 

 all combine to indicate in a very striking manner, if not to demonstrate, that the 

 conical head of the present species, which is comparatively small and slender, and 



