ORDER VI 



CHELONIA 



199 



however, are too imperfectly known to admit of a precise account of their 

 structure or taxonomy. 



Propleura and Peril resins, Cope, from the Upper Cretaceous of the United 

 States, are represented by a few species, all under 1 m. in length. Desmato- 



FiG. 301. 



Thalassochelys caretta, Lion. sp. Recent; Mediterranean. Ventral aspect 

 of skeleton, the plastron removed, cor, Coracoid ; h, Humerus; psc, I'tv- 

 coracoid (" prescapnla," Banr); r, Radius; sc, Scapula; u, Ulna. 



Fig. 302. 



Chi h o fni a ii a i. i i iay. 



Upper Cretaceous; Maestricht, 

 Holland. Portion of carapace, ' g. 



chelys, Williston, from the Fort Benton Cretaceous of Kansas and Nebraska, is 

 a peculiar form with some aberrant characters, such as free nasals, stout 

 transverse processes on the cervical vertebrae, and a single articular face on 

 the posterior cervicals. Puppigerus, Cope, occurs in the Miocene of New Jersey. 



Superfamily 2. CHELYDROIDEA. Baur. 



No parieto-squamosal arch; a foramen palatinum between palatine and maxilla ; 

 articular faces between the sixth and seventh cervical vertebrae not plane; riuchal 



without lower process, hut with more or less strong lateral process underlying fin 

 peripherals; <>nr biconvex cervical; a complete series of inframarginals. 



Family 1. Thalassemydidae. Riitimeyer. (Acichelyidae, Lydekker.) 



Temporal fossae of skull partial/// roofed. Shell cordiform, more or less in- 

 completely ossijin], the fontanelle in plastron persisting for a long period or throughout 



