ORDER VI CHELONIA 203 



Ptijcliogaster, Pomel. Neural bones short ; pleurals alternately long and 

 short at their inner and outer extremities ; nuchal emarginate. Hyoplastrals 

 united to the carapace by suture, the hypoplastrals joining it by a straight 

 ligamentous union, and movable upon a transverse hinge. Oligocene or Lower 

 Miocene ; France. 



Stylemys, Leidy. Skull unknown. Shell with the general characters of 

 Testudo, but with all or nearly all of the neural bones hexagonal, with short 

 antero- lateral surfaces ; the nuchal not emarginate; posterior caudals not 

 alternating in length ; caudal shield undivided. Oligocene to Pliocene ; 

 Western United States. S. nehmsccnsis, Leidy, the type species, is very 

 abundant. 



CisfiidOj Fleming (Fig. 299) ; Cycle7nys, Bell. Recent. Damonia, Bellia, 

 Nicoria, Gray. Pliocene and Recent, Ocadia, Gray ; Clemmys, Wagler. 

 Miocene to Recent. 



Family 2. Testudinidae. Gray. (Chersidae.) Land Tortoises. 



Skidl with open temporal fossae ; quadrate dosed hehiiul. Shell compleiely 

 ossified even in the young, more or less ovoid, and covered with epidermal shields. 

 Plastron suturally united with the marginals ; an entoplastron present. Sternal 

 hridge long, sternal Chambers very slightly developed ; anterior and posterior extremities 

 of hyo- and hypo-plastron little extended inwards ; marginals of hridge with median 

 processes interlocking with rib ends. Shdl with open temporal fossae ; quadrate closed 

 behind. Pubic and ischiadic symphyses firmly connected with each other. Limbs with 

 free digits, which are short and moderat ely elongate ; terminal claws four or five. 

 Second and third digit of pes never with more than two phalanges. Tertiary and 

 Recent. 



Cinixys, Bell {Kinixys, Bell ; Cinothorax, Fitz.). Posterior portion of cara- 

 pace movable in the adult, hinged between the seventh and eighth marginals 

 and the fourth and fifth pleurals. Gulars distinct. Recent ; Africa. 



Pyxis, Bell. Carapace without hinge ; front lobe of plastron mobile. 

 Recent. 



Homopus, Dum. and Bibr. Carapace and plastron without hinge. Palate 

 without oral ridge. Eocene to Recent. 



Hadrianus, Cope. Distinguished from Testudo by the narrow vertebral 

 shields, usually hexagonal neural bones, undivided caudal shield, and more 

 uniform length of extremities of the pleural bones. Eocene ; North America. 



Testudo, Linn. {Colossochelys, Falc. and Caut. ; Manouria, Gray ; Xerobates, 

 Ag.). Neural bones short ; pleurals alternately short and long at their inner 

 and outer extremities ; nuchal deeply emarginate. Plastron extensively united 

 with the carapace by suture ; buttresses short, never extending beyond the 

 edge of the costals. Vertebral shields broad, costals very short. Miocene to 

 Recent. Some Pliocene species attain gigantic size, the shell of T perpiniana, 

 Deperet, from the Pliocene of France, having a length of 1-2 m., and that of 

 T. atlas, Falconer and Cautley, from the Pliocene of the Siwalik Hills, India, 

 upwards of 2 m. 



Sub-Order C. PLEURODIRA. Dumöril. 



Skull with outer border of tympanic cavity completely encircled by the quadrate ; 

 Ijterygoids very broad throughout, forming wing-like lateral expansions, and not 



