6 



Order 11. CHELONIA. 



Quadrate bone immovably united to cranial arches. Dorsal ribs 

 single-headed, the anterior attached between two vertebrae. Body 

 encased in a bony shell. A plastron formed of a small number of 

 elements in addition to the clavicles. No sternum. No teeth ; 

 jaws covered with horny sheaths. Anal opening round or 

 longitudinal. Copulatory organ present, single. 



Oviparous ; eggs with a hard shell, except in the CJielonidce. 



The Tortoises and Turtles of India fall into five Families*. 



Suborder I. THECOPHORA. 



Dorsal vertebrae and ribs immovably united and expanded into 

 bony plates forming a carapace. Parietals prolonged downwards 

 towards the pteiygoids. 



Superfam. A. TEIONYCHOIDEA. 



Articulation between the last cervical and the first dorsal 

 vertebra by the zygapophyses only. Marginal bones absent or 

 forming an incomplete series. 



Carapace and plastron without epidermal shields, 



covered with a soft skin Fam. 1. Trionychidae. 



Superfam. B. CETPTODIRA. 



Centrum of the last cervical vertebra articulating with the 

 centrum of the first dorsal. A complete series of marginal bones, 

 connected with the ribs. 



Digits short ; tail short, with proccelous ver- 



tebrPB Fam. 2. Testudinidae. 



Digits .short ; tail long ; caudal vertebrae mostly 



opisthoccelous Fam. 3. Platysternidae. 



Limbs paddle-shaped, with only one or two claws. 



Marine Fam. 4. Chelonidae. 



Suborder II. ATHECyE. 



Vertebrae and ribs free, separated from a bony exoskeleton. 

 Skull without descending processes of the parietal bones. 



Limbs paddle-shaped, clawless. Marine.... Fam. 5. Sphargidae. 



* These five families, so far as Indian genera are concerned, may be recog- 

 nized from external cbaracters by use of the following key : — 



Limbs witli foiu- or five claws. 



Tail short Testudinidae. 



Tail nearly as long as the sliell Platysternidae. 



Limbs \\ith three claws Trionychidae. 



Limbs with one or two claws Chelonidae. 



Limbs witliout claws Sphargidae. 



