566 



REPTILES. 



to one another on each side. The males have a grooved penis attached 

 to the anterior wall of the cloaca. There is a urinary bladder. 



Classification of Chelonia. 



I. Athec/e. Vertebra and ribs free from carapace. Skull 

 without descending processes from parietals. 



Sphargidse, leathery-skinned turtles, with flexible carapace. Sphargis 



(Dermatochelys) cori- 

 acea, the only living 

 species, the largest 

 modern Chelonian, 

 sometimes measuring 

 6 ft. in length. It is 

 widely, but now spar- 

 sely, distributed in in- 

 tertropical seas, and 

 is said to be herbivor- 



II. Thecophora. 

 Dorsal vertebrae 

 and ribs fused in 

 the carapace. 

 Parietals pro- 

 longed down- 

 wards. Including 

 the following and 

 other families : — ■ 

 Chelonidse, marine 

 turtles, with fin-like 

 feet, and partially os- 

 sified carapace. They 

 occur in intertropical 

 seas, and bury their 

 soft-shelled eggs on 

 The 



Fig. 245.- 



-Heart and associated vessels of tortoise. 

 —After Nuhn. 

 r.a., Right auricle ; superior venae cavae (s.v.c.) and 

 inferior vena cava (i.v.c.) enter it. r.zi. Right half of Sandy shores, 

 ventricle ; pulmonary arteries ip.a.) and left aortic green turtle {Chelone 

 arch (Aao.) leave it ;ot/. cceliac ; d.ao., dorsal aorta. OT >»tfft) j s muc h es _ 

 1. a., lieftauricle ; p.v., pulmonary veins enter it. l.v.. . j r , ., 



Left half of ventricle ; right aortic arch (r.ao.), giving teemed as food; the 

 offcarotids(c.)andsubclavians(j.r/.). hawk's-bill turtle 



( Caretta imbricatd) 

 furnishes much of the commercial tortoise-shell. 



Testudinidae, land tortoises, with convex perfectly ossified carapace 

 and feet adapted for walking. They are found in the warmer regions 

 of both the Old and the New World, but not in Australia. In diet they 

 are vegetarian. The common tortoise ( Testudo grceca) and the extermin- 

 ated giant tortoises of the Mascarene and Galapagos Islands are good 

 representatives. 



Chelydidse, fresh-water tortoises, more or less aquatic, with per- 

 fectly ossified carapace, and feet with sharp claws. Examples.— Chelys 



