42 



GUIDE TO EEPTILES AND AMPHIBIANS. 



:). Trionychoidea, or those with very flat oval or almost round 

 shells, covered with soft leathery skin, and broadly webbed 

 limbs, of which only the three middle toes are clawed. 



The following table shows the chief sub-divisions of the group : 



Order 



I. Section Athene. 

 Family Spharnida'; or 



Dermochelydidci' . 



11. Section Thecophora. 



i. Sub-order Cryptodira. 

 Family Chelydridir. 

 ., Dermatemydidre. 

 ,, Ginosternidce. 

 ,, Platysternid(B. 

 ., Testudlnid(r.. 

 dieloiiidtr. 



CHELONIA. 



j ii. Sub-order Pleurodira. 

 ' Family Pelomediisida'. 

 ,, Chelydidd'. 



Carettoclielydidce. 

 Flesiochelydidce.) Ex- 

 ,, Miolaniida'. jtinct. 



iii. Sub-order Amphichelydia. 

 Family Fleurovteniidce 



(extinct). 



iv. Sub-order Trionychoidea. 

 Family Triony<:]i idfi'. 



Fig. 43. 



Upper (.4) and Lower (B) Shells of the Greeu Turtle (Chelone viydas), to show 

 arrangement of the horny plates. 



n. Nuchal. 

 I'. Vertebral. 

 c. Costal. 

 »i. Marpriiial. 



sc. Supracaudal. 

 im. Inframarginal. 

 iff. Intergular. 



0- Gular. 

 h. Humeral. 

 j>. Pectoral. 



o. Abdominal. 

 /. Femoral. 

 an. Anal. 



