in North America of rare Extinct Vertebrates. 205 



pression, which probably lodged a corresponding saccular 

 process of the lung. On one side this depression was parti- 

 ally divided by a thin oblique plate (pi. v. fig. l,f,f) ; its 

 relative position beneath the base of the diapophysis is shown 

 atc^"*. 



So also in the " enormous Saurian of the Dakota group," 

 "just beneath the diapophysis is situated a huge foramen "f* 

 And in Prof. Cope's subsequent and fuller description, " the 

 centra of the cervicals and dorsals are hollow, and the interior 

 chambers communicate with the cavity of the body by a large 

 foramen on each side, which is below the base of the diapo- 

 physis. In the cervical region it is very elongate, and ex- 

 tends between the bases of the parapophysis and diapophy- 

 sis " t- 



6. General Proportions and Shape. 



The centrum of the anterior trunk-vertebrae of Chondros- 

 teosaurus, the subject of plates ii., iv., and v. fig. 1, is notable 

 for its great longitudinal and small vertical diameter and 

 the flatness of the under surface (PI. X. fig. 1). 



So likewise with the Dakota Saurian, " The supposed cer- 

 vical vertebra is depressed; the anterior or convex extremity 

 is the most so. It is remarkable for its elongate form, exceed- 

 ing the proportions found in known Dinosauria and Croco- 

 dilia "§. In truth the only known vertebra of considerable 

 proportions was the subject described and figured, under the 

 heading " Order Dinosauria (?) j Genus Ghondrosteosaums ; 

 species Ghondrosteosaums gigas^ Owen," in the Monograph 

 of 1876. 



7. Size. 



But, huge as were the fossil vertebrae from the Wealden, 

 which suggested the nomen triviale, they are surpassed by 

 the subjects of Prof. Cope's description. 



The length of my specimen was 1 foot 3 inches ; and I ven- 

 tured to state, with respect to this dimension, that the vertebra 

 equalled " in length the largest one of any Cetacean recent or 

 fossil "i|. 



Of the Dakota monster Prof. Cope states, " the dimensions 

 of the animal to which they belonged may be inferred from 

 the fact that the first [cervical vertebra] is twenty inches 



* Monogi-., Pal. Soc. vol. 187G, p. 6. 



t Pal. Bull. no. 2o, 1877, p. 5. 



X Proc. of Amer. Phil. Soc. 1877, p. 236. 



5 Pal. Bull. no. 25, 1877, p. 5. 



il Monogr. 1876, p. 6. 



