414 



CHELOXIA. 



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 horny 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 Chelonemydidae 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 

 horny shields except in 

 Carettochelys. 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 nuchal 

 shield ; plastral bones 

 1 1 ; 2nd cervical verte- 

 bra biconvex. Africa, 

 Madagascar, S. Amer- 

 ica. Stern othaerus 

 Bell, skull without 



supratemporal roof, quadrate -jugal widely separated from pari- 

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

 medusa, \VagL, 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 Dumer., digits webbed, S. Amer. 

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

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

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

 New -[Guinea. Rhinemys Wagl., S. Amer. ; Hydraspis Bell, S. Amer. ; 

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

 Elseya Gray, Australia. 



FIG. 233. Thalassochelys caretta (RSgne animal). 



