TESTUDLNID.E. CXXIII. 211 



ing obscure with age. N. Y. to Mo. and S., in dry woods. Repre- 

 sented S. by var. triunguis (Agassiz). Hind feet mostly 3-toed ; 

 color pale yellowish, with few spots. Southern, N. to Penn. 



624. C. ornata Agassiz. " Shell round, broad, flat, without keel, 

 even when young." Iowa and \V. 



FAMILY CXXIII. TESTUDINID^J. (THE LAND 

 TORTOISES.) 



Carapace strong, thick, ovate, generally very convex and falling 

 off abruptly at both ends ; caudal shields united into one ; plastron 

 very broad, covering the whole under surface, the anterior part 

 sometimes movable on a transverse hinge. Legs and feet club- 

 shaped; toes firmly bound together by the integument, only the 

 blunt claws being exserted. 



Herbivorous Turtles, entirely terrestrial, inhabiting the warmer 

 parts of both continents ; about 20 species are known. 



317. XEROBATBS Agassiz. (;pos, dry ; ftdrrjs, walker.) 



625. X. polyphemus (Daudin.) " GOPHER TURTLE." Brown- 

 ish, head almost black ; yellow below ; fore limbs large and strong ; 

 hinder short, rounded ; plastron projecting forward beyond cara- 

 pace. L. 15. S. States, N. to N. C., in pine barrens; herbivo- 

 rous and gregarious ; burrows in the ground like a wood-chuck. 

 (iroXixfrrjfjios, croaking.) 



Passing over the order CROCODILIA, the highest in development 

 among the recent reptiles, an order having no representatives 

 within our limits, we take up next a group originally an offshoot 

 from the Reptilian series, but now, if only living forms were taken 

 into consideration, one of the most sharply defined of the classes of 

 Vertebrata, the Birds. 



