REPTILES. 



between the temperature of their bodies and that 

 of the air or water in which they live, is not sen- 

 sible to the touch. The Sub-class Amphibia, 

 including the Frog-like Reptiles, pass through a 

 sort of metamorphosis, breathing by means of 

 gills in their early stages ; and there are a few 

 which have both gills and lungs through their 

 entire existence. 



The senses are in general well developed, 

 though in various degrees in the different Orders : 

 in some, however, the sense of sight appears to 

 be nearly obliterated, as in Typlilops, and in Pro- 

 teus. Their brain is comparatively small ; and 

 their sensations seem less referrible to a common 

 centre, than in the higher Classes : life, and even 

 voluntary motion, continues long after the brain 

 is removed ; the irritability of the muscular fibre 

 is preserved for a considerable time after sepa- 

 ration from the rest of the body; and the 

 heart pulsates for many hours after it has been 

 detached. 



" The motion of Reptiles is as various as their 

 structure, and exhibits a great diversity, particu- 

 larly in the modes of progression. The slow march 

 of the Land Tortoise, the paddling of the Turtles, 

 the swimming and walking of the Crocodiles, the 

 Newts, and the Protei, the agility of the Lizards, 

 the rapid serpentine advance of the Snakes, the 

 leaping of the Frogs, offer a widely extended 

 scale of motion. If we add the vaulting of the 



