ORDER VI 



CHELONIA 



199 



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

 structure or taxonomy. 



Propleura and Ferifresius, Cope, from the Upper Cretaceous of the United 

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



FiG. 301. 



Fig. 302. 



Thalassoehelys cardia, hiun. STp. Recent ; Mediterranean. Ventral aspect Chelone hofmanni, Gray, 



of skeleton, the plastron removed, cor, Coracoid ; /(,, Humerus ; ^wc, Pre- Upper Cretaceous ; Maestricht, 

 coracoid ("prescapula," Baur) ; r, Radius; sc, Scapula; m, Ulna. Holland. Portion of carapace, i/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. 



JSfo par ieto- squamosal arch ; a foramen palatinum between palatine and maxilla ; 

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

 without lower process, but with more or less strong lateral process underlying the 

 peripherals ; one biconvex cervical ; a complete series of inframarginals. 



Family 1. Thalassemydidae. Rtltimeyer. {Acichelyidae, Lydekker.) 



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

 completely ossified, the fontanelle in plastron persisting for a long periods or throughovf 



