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Class 2. Reptilia. 



Reptiles are cold-blooded vertcbrata, which breathe by means of lungs, 

 or lungs and gills. The heart is composed of a large ventricle with which 

 the two auricles communicate. The ventricle receives venous blood from 

 the system through the right auricle, and oxygenated blood from the lungs 

 through the left one, so that both pure and impure blood are mixed in the 

 ventricle, previous to being sent through the system, a portion passing- 

 through the lungs. This jieculiarity of the circulation accounts for these 

 animals being cold-blooded, since in the animals with warm blood, one of 

 the two ventricles transmits unmixed oxygenated blood to the system. 



The brain of reptiles is small, and exercises less influence upon the 

 system than in the higher classes, since they can live a considerable time 

 when it is removed. The body is naked or covered with scales, but these 

 are unlike those of fishes. The first order is named BatnicMa by Cuvier, 

 and Amphibia by other authors, on account of their adaptation to breathing 

 both air and water at the same time, or at different periods of their life. In 

 some of the amphibia the gills are permanent {Gnesiobranchiata), and in 

 others they disappear {Agiics'iohranchiata). 



Order 1. Batrachia. PI. 74, ßgs. 59, Salamandra; 60, Rana. 

 " 2. Ophidia. " " 61, Vipera; 62, Boa. 



" 3. Sauria. " " 63, Anguis; 64, Ophisaurusj 65, 



Chirotes ; QQ, 67, Chalcides; 68, Bipes ; 69, Anolis ; 70, 

 Sdncus ; 71, Tilicua; 72, ChamoiUo; 73, Ptyodactylus ; 

 ^4:., Basiliscus ; 15., Iguana; 1Q., Draco ; 77, Aga7na; 78, 

 Stellio ; 79, Lacerta; 80, Tejus; 81, Crocodilus; 82, 

 PlesiosauTus ; 83, Ichthyosaurus. 

 Order 4. CnELONmEA. PL 7^, figs. 84, Chelonia; 85, Testudo. 



Class 3. Aves. 



Birds are oviparous vertebrata, with warm blood and a double circulation, 

 (lothed with feathers, and provided with two feet and two wings. The air 

 has access to various parts of the bod}", which diminishes their specific 

 gravity, and assists them in flight. Of all the classes of animals this is the 

 most strictly defined ; and its characters are more uniform, and have 

 fewer exceptions, on which account the classification presents some 

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