42.'? 



Chapter IX. 



MAMMALIA. 



§ I . Mammalia in general. 



The singular animals, so remarkable for their 

 anomalous shapes, their torpid vitality, and their 

 amphibious constitution, which have lately oc- 

 cupied our attention, appear placed by nature as 

 forms of transition in the passage from those verte- 

 brated animals which dwell in the water, to those 

 which inhabit the land. The class of 3IammiJha, 

 or Mammalia, comprehends all the animals which 

 possess a spinal column, breathe air by means of 

 lungs, and are also warm-blooded and viviparous ; 

 conditions which render it necessary that they 

 should possess organs, called mammce, endowed 

 with the power of preparing milk for the nourish- 

 ment of their young ; a peculiarity from which the 

 name of the class is derived. But they are not ex- 

 clusively land animals ; for among the mammalia 

 must be ranked several amphibious and aquatic 

 tribes, such as the Seal, the Walrus, the Porpus, 

 the Dolphin, the Narwhal, the Cachalot, and the 

 Whale ; animals which, however widely they differ 

 in their habits and external conformation from ter- 

 restrial quadrupeds, possess, in common with the 

 latter, all the essential characters of internal struc- 

 ture and of functions above enumerated. These 

 characters belong also to the human species, which 

 must consequently, in its zoological lelations, be 



