246 FOSSIL REPTILES. 



dered together. Of the atlas was preserved only its lower 

 piece, and a part of its lateral pieces destined to embrace the 

 condyle of the occiput. All that had contributed to form the 

 canal had disappeared. The axis is more complete, having 

 lost only the hinder part of its annular piece. Many characters, 

 even in this specimen, indicated a species different from that of 

 the gavial of the Ganges and all other living crocodiles. The 

 tubercle of the axis showed that the false rib of this vertebra 

 had two heads, as well as those of the succeeding cervical verte- 

 brae. In the crocodile and gavial there is but one. The pos- 

 terior face of the body of the axis is concave ; while it is convex 

 in all known crocodiles. From these, and many other fragments 

 found in the same neighbourhood, M. Cuvier has established 

 that there was one species here exhibiting a peculiar vertebral 

 system in which the vertebrae are convex in front. This he 

 calls the convex system. 



But there were also found in the same places, and mixed up 

 with the former fragments, others demonstrating a very different 

 system, which Baron Cuvier terras the concave si/stem. The 

 vertebrae which compose it have not the body narrowed in the 

 middle. Their transverse apophyses do not spring from the 

 union of many salient crests. They much more resemble those 

 of our living crocodiles ; but their principal difference, both 

 from our living species and the first fossil species, is, that nei- 

 ther of the faces of their bodies are convex, but both slightly 

 concave. As to the rest, they have the sutures, and all the 

 arrangement of apophyses which characterize, generically, the 

 vertebrae of crocodiles. M. Cuvier is inclined to refer the ver- 

 tebrae of the first system, or the convex, to the first jaw which 

 we described from the Honfleur remains- — that belonging to a 

 shorter and more obtuse muzzle. As that least resembles the 

 living crocodiles, it seems natural to refer to it the vertebrae 

 which least resemble theirs. Be this, however, as it may, the 

 clear distinction of all the fossil fragments found in the places 

 which we have described, from all that characterizes living 



