NATURAL SCIENCES OF PHILADELPHIA. IT 



been less concavity of this margin than in that turtle. The 

 suture between the two is also peculiar in not underrunning the 

 marginal to the same extent, and a portion of it underruns the 

 nuchal. It is indeed possible that these bones represent the 

 caudal and adjacent marginals, but the presence of a fragment 

 bearing the support of a vertebra is more suggestive of the nu- 

 chal. 



A prominent peculiarity of the bone is its great thickness. The 

 first marginal near its suture with the second, measures an inch 

 and three-quarters. The free margin is very thick and obtusely 



rounded. 



jr. 



Estimated length first marginal (one edge broken) . . 0.15 



Thickness near suture of second .045 



" of nuchal .... ... .033 



Should the size of this turtle be proportioned to the thickness 

 of the carapace, or to its relation to corresponding parts of the 

 L. prox>ylaeu$, it will have been one of the largest species of the 

 order, say from ten to twelve feet in length. 



The above descriptions leave much to be desired in regard to 

 the characters of the genus. The peculiarities of the sutures 

 distinguish the form from Chehjdra, and the association with an 

 especially marine fauna suggests natatory limbs like those of Pro- 

 pleura or Chelone. 



CROCODILIA. 



THECACHAMPSA SQTJANKENSIS (?Marsh). 



Amer. Journ. Sci. Arts, 1869, 391 {no description). Cope, Trans. Amer. 

 Philos. Soc, 1869, 65. 



Squankum. 



THECACHAMPSA SERRATA, Cope, sp. nov. 



Established on cervical and dorsal vertebras of an adult croco- 

 dile of about the size of a South American jacare (J. sclerops). 

 The teeth are not preserved, so that reference to this genus is 

 only made in consequence of the simple form of the hypapopl^ses 

 of the cervical vertebras, a character belonging also to other 

 genera. The neural arches and odontoid element are co-ossified. 

 The axis is compressed concave laterally, and with a very pro- 

 minent 113'papophysial extending on the anterior half keel of the 

 body. The parapophj'ses are inferior or on the lower plane, and 

 1872.] 



