VERTEBRATA. 209 



The Chelonia are very sluggish in their movements, very tena- 

 cious of life, and are said to pass even years without food. 

 [Cuvier.] They are oviparous, and live mostly on vegetable food ; 

 Trionychidse are carnivorous. In their jaws deprived of teeth 

 they resemble birds. Their anal cleft is longitudinal. 



This order includes the green-turtle ( Chelonia midas), tortoise- 

 shell or hawk's-bill turtle (Chelonia imbricata), logger-headed 

 turtle (Thalassochelys caretta), terrapin (Emiys sps.), box- tortoise 

 (Cistudo carinata), alligator-tortoise (Chelydra serpentina), and 

 soft-back ( Trionyx ferox). The common tortoise is Testudo grceca. 



Several gigantic species of tortoise ( Testudo), living and extinct, 

 are known ; the former are now almost entirely confined to the 

 Galapagos and Aldabra islands, the latter to Mauritius and Eocl- 

 riguez. Colossochelys atlas, an Indian fossil species, is said to 

 have been 20 feet in length. 



There are about 200 good species in this order, which have been 

 distributed into 103 so-called genera, many of them, according to 

 Giinther, depending on slight differences of the skull, but unac- 

 companied by any external characters. 



CheloniidcB. Chelydidce. Clemmys. 



Sphargis. Emydura. Chelydra = Chelo- 



Thalassochelys= Hydraspis. nura. 



Caouana. Podocnemis. Emys (Terrapin). 

 Chelonia (Turtle). Pelomedusa. 



Chelys. Testudinida. 



TrionychidcB. Teleopus. 



Emyda. Emydida. Cinyxis. 



Trionyx. Cinosternum. *Colossochelys. 



Cistudo. Testudo (Tortoise). 



Order X. THEEIODONTIA. 



Incisors defined by position, and divided from the molars by a 

 large laniariform canine on each side of both jaws, the lower 

 canine crossing in front of the upper. No ectopferygoida. The 

 huruerus with a supracondylar foramen. 



The supra condylar foramen is one of the characters of the 

 Felidae. In this and certain other respects the Theriodontia had 

 mammalian resemblances. Owen has described many genera and 

 species whose remains have been found in the Triassic lacustrine 

 deposits of South Africa. 



*Cynodraco. *Tigrisuchus. *Galesaurus. 



p 



