ON ZOOLOGY. 106 



though red, is of a lower temperature than the 

 common atmosphere, and therefore they have 

 been denominated cold, red-blooded animals. 

 They consist of the perfect fishes, (whales ex- 

 cepted) land and sea tortoises, frogs, toads, 

 lizards, and the various species of serpents. 



To the third and last division belong those ani- 

 mals, which, with a doubtful heart, in the place 

 of red blood have only a cold, whitish, and near- 

 ly colourless fluid, and these in consequence 

 have been denominated, cold, ivhite blooded ani- 

 mals. To this division belong the insect families, 

 and the crustaceous shell fish ; and the worm 

 tribes, including the testaceous shell fish, and 

 zoophites. 



Taking the above as a basis, the six classes of 

 Linnreushave been formed in the following order. 



Firstly. Mammalia, warm, red blooded animals, 

 with a double heart, which give suck to their 

 young, and are viviparous, including our own spe- 

 cies, land quadrupeds, and the whale tribes. 



Secondly. Aves, warm red blooded animals, with 

 a double heart, which are oviparous ; including 

 the different species of birds. 



Thirdly. Amphibia, red cold blooded animals, 

 with a single heart, and breathing with lungs, of 

 which they have the voluntary command so as to 

 suspend respiration for a very extraordinary time 

 at pleasure without injury to themselves, consist- 

 ing of land and sea tortoises or turtles, frogs, 



