in North America of rare Extinct Vertebrates. 211 



fig. 1) in PI. X. fig. 3, illustrating the present communica- 

 tion. This concordance, indeed, between the Wealden Chon- 

 drosteosaur and the Dakota gigantic Reptile may be reckoned 

 as an eighth character and evidence of their generic relation- 

 ship. In further illustration of this significant indication of 

 the sphere and grade of locomotion in my reptile, I added the 

 figure of a corresponding view of a vertebra of an eagle 

 (PI. X. fig. 6) *. 



It was rather hard, after the pleasurable pains which I 

 had taken to make my few vertebrae as useful as possible 

 to future finders, to have my proposed generic name super- 

 seded by Camarosaurus^ Cope, and still harder to read, 

 in the Professor's excellent supplementary notices of the 

 genus, " Another name ( Chondrosteosaurus) has been intro- 

 duced by Prof. Owen ; but he specifies no generic characters "f. 



A name, notwithstanding Linn^'s estimate |, interests me 

 less, in the present case, than the nature and affinities of the 

 gigantic Saurian in question ; and towards the latter know- 

 ledge Prof. Cope's descriptions give acceptable and valuable 

 aid. 



On the limited foundation to this end available in 1876, I 

 was led to refer Chondrosteosaurus to the Dinosaurian order, 

 but with a sign of doubt §. 



A sacrum, part of a sacrum, perhaps a single sacral vertebra 

 might have dispelled the doubt. Mr. Lucas was so fortunate 

 as to secure the entire sacrum of the Dakota reptile. Its 

 small size and an inference as to its function are noted above. 

 Prof. Cope has added to that notice the following descrip- 

 tion : — 



" It consists of only four vertebral centra, thoroughly co- 

 ossified. The anterior articular extremity is convex, that of 

 the posterior extremity slightly concave. Its transverse pro- 

 cesses are, like those of the other vertebrae, much elevated, 

 although they spring from the centra. The external face of 

 their bases is not prominent ; and the spaces between their 

 projecting portions are deeply excavated. The extremities of 

 the adjacent transverse processes are united, thus inclosing 

 large foramina "||. 



In tlie Dinosaur of the skeleton of which we have the most 

 complete restoration (i. e. Scelidosaurus) , the sacrum con- 

 sists of four coalesced vertebrae ; the transverse processes are 



« MonogT. 1876, pi. iv. fig. 3. 



+ Bullet, cit. p. 6. 



X " Nomina si pereunt, periit et coguitio rerum.'* 



§ Monogr. 1876, p. .'5— " Order Dinosauria (?)." 



II Proceedings of the Amer. Philos. Soc. 1867, p. 235. 



