MANUAL OF NATURAL HISTORY. 69 



II. SUB-CLASS. — Shielded-Eeptiles (Cataphracta). 



Body covered with square imbedded plates, 

 generally forming a dorsal and a ventral shield ; 

 bones of skull thick, united into a hard mass ; tongue 

 short, affixed to mouth, scarcely exsertible ; jaws 

 united into a solid mass ; mouth not dilatable ; vent 

 round or linear, plaited ; oviparous ; egg with a hard 

 sheU. 



I. ORDER — Chelonians (Chelonia). 



Body short, depressed, enclosed in a case, formed 

 by two shields united at their margins ; jaws tooth- 

 less ; upper bill covers lower like a box ; eyes with 

 distinct eyelids ; drum of ear visible ; legs short, 

 thick ; tail conical ; vent circular. 



1. Family. — Land-Tortoises (Testudinidse). Head 



ovate, shielded ; jaws naked ; nostrils apical ; 

 neck retractile ; feet short, club-shaped; claws 

 5-4, or 4-4, blunt ; shell very solid, thick, 

 ovate ; tail short, thick ; slow moving. 



2. Family. — River-Tortoises (Emydidse). Head 



rather depressed ; jaws naked; nostrils apical, 

 small ; feet depressed, palmate ; toes 5-5, or 

 4-4, mostly webbed to the claws ; claws sharp ; 

 tail conical, shielded beneath ; thorax gene- 

 rally depressed ; pelvis united to vertebrae 

 only; sternal shields 11 or 12 ; egg oblong, 

 white ; carnivorous ; rapid. 



3. Family. — Long-necked Tortoises (Chelydidse). 



Head much depressed, broad ; nostrils elon- 

 gate, tubular ; eyes superior ; jaws horny ; 



