414 



OHELONIA. 



oceans, shell to 4 ft., herbivorous, the dense subcutaneous connective 

 tissue (callipash and callipee) within the shell, as well as the fat and meat, 

 is used in preparing the soup ; eggs round, parchment-shelled ; Ch. imbri- 

 cata, the hawksbill turtle, shell to 34 in., their homy epidermal shields are 

 used as tortoise shell ; Thalassochelys Fitzing., Th. caretta L. (Fig. 233), 

 the loggerhead turtle, trop. and sub trop. seas. 



Two extinct families are allied here : — 



The Chelonemydldae and the Thalassemydidae from the Jurassic, Cre- 

 taceous etc. 



Section 2. Pleurodira. 



Neck bending laterally ; pelvis fused to the shell, the ilia to the carapace, 

 the pubes and ischia to the plastron. Freshwater tortoises almost en- 

 tirely carnivorous, inhabiting S. America, Australia, Africa, and Mada- 

 gascar ; fossil forms from the Jurassic. The temporal region of the skull 



is variable. The cara- 

 pace is covered with 

 homy shields except in 

 Garettochelys. Extinct 

 forms are known from 

 Trias and Jura of Eu- 

 rope, and are the old- 

 est fossil Chelonia. 

 {Psammochelys Quenst. 

 =^Proganochelys Baur, 

 Keuper Sandstone.) 



Fam. 1. Pelome- 

 dusidae. Neck com- 

 pletely retractile with- 

 in the shell ; carapace 

 without a nuohal 

 shield ; plastral bones 

 1 1 ; 2nd cervical verte- 

 bra biconvex. Africa, 

 Madagascar, S. Amer- 

 ica. Stern othaerus 

 Bell, skull without 

 supratemporal roof, quadrato-jugal widely separated from pari- 

 etal, digits short, 5 claws, trop. and S. Afr., Madagascar ; Pelo- 

 medusa, Wagl., skull with a slender parieto -squamosal arch, digits short, 

 5 claws, Africa and Madagascar ; Podocnemis Wagl., supratemporal roof 

 formed by junction of parietal with quadrato-jugal, digits webbed, 

 5 claws on fore- and 4 on hind-foot, S. Amer., Madagascar ; P. expansa, 

 Arran turtle, edible, eggs collected for oil, S. Amer. 



Fam. 2. Chelydidae. Plastral bones 9, temporal region diverse, S. 

 Amer., Australia, New Guinea. Chelys T>woa6r., digits webbed, S. Amer. 

 and Australia, Ch. fimbriata Schn., the matamata, aquatic. Hydro- 

 medusa Fitz., digits webbed, long neck, S. Amer. Chelodina Fitz., long 

 neck, neural plates absent, costals meeting, digits webbed, Australia and 

 New Guinea. Rhinemys Wagl., S. Amer. ; Hydraspia Bell, S. Amer. ; 

 Platemya Wagl., S. Amer. ; Emydura Bon., Australia and New Guinea; 

 Elseya Gray, Australia. 



Fig. 233. — Thalassochelys caretta (Rdgne animal). 



