CLASS REPTILIA: ORDER TESTUBIJiTATA. 



165 



CLASS III. REPTILIA. 



General Characteristics (see Table, p. 13).— Reptiles*, 

 being cold-blooded, require nothing to retain the heat, and 

 so are covered only with naked skin, scales, etc. The three- 

 chambered heart does not send all the venous blood to the 

 lungs. Pure oxygenated blood, however, goes to the head. 

 Eeptiles are most abundant in hot climates, those of cold 

 regions hibernating. They are generally carnivorous, and 

 swallow their prey whole. 



— -a 

 I— o 



a. DO 



lU 



NEARLY COVERED WITH A BONY OR HOENY 



CASE WHICH BLENDS WITH THE NEDRO- 



SKBLETON. 



COVERED WITH SQUARE PLATES. . 



COVERED WITH 

 IMBRICATE SCALES ; 



' Mouth not hilatable ; 

 legs generally devel- 

 OPED, EYES WITrii LIDS. 



Mouth dilatable 

 legs, no ete'lids. 



NO 



Testodinata, Tortoiee, etc 



Loricata, AUigator, etc 



Lacertilia, Zixard, etc, 



[ Opbldia, Sndktf etc 



ORDER TESTUDINATA. 



General Characteristics.— The Turtles have the skel- 

 eton on the exterior of the body. The vertebrae and ribs are 



Mg. ««. 



Skeleton of Muropean Tortoise. 



* There eeems little resemblance between a crawling reptile and a flitting song- 

 ster ; yet, in stmcture, reptiles are mucli nearer related to birds than to mammals. 

 This is shown especially in the fossil, reptile-like bird, Archaiopteryx, and the bird- 

 like reptiles, Dinosauria and OmithosauHa. See Geology, page 183-5. 



