MAMMALIA. 205 



chambers, two auricles and two ventricles, wliicli 

 receive the blood in the following succession : — 



Lungs. 



Veins. 

 Left auricle. 

 Left ventricle. 



Arteries. 



Capillaries. 



Veins. 

 Eight auricle. 

 Right ventricle. 



Ai'teries. 



Lungs. 



In general, the animals of this Class are furnished 

 with two pairs of limbs, fitted for walking on the 

 solid ground ; but those which we have to notice 

 are adapted for aquatic life, and hence their 

 structure is modified with a view to this adapta- 

 tion. The Seals, which possess the usual number 

 of limbs, have them shortened, enveloped in skin, 

 and so placed as to perform the office of fins rather 

 than legs, as indeed they resemble in appearance 

 those fish-like organs. But in the Whales, the 

 fore limbs are still more decided fins, wliile the 

 hinder extremities are wholly wanting, their place 

 being supplied by a broad horizontal caudal-fin: 

 many of the species are also furnished with a proper 

 dorsal. 



Notwithstanding this fish-like form, however, 

 the Whales and Dolphins have no real affinity 

 with Fishes, but are true Mammalia ; bringing 

 forth living young, nourishing them with milk, 

 having warm blood, a perfect circulation, and 

 breathing air by means of internal lungs. 



Localities, &c. — The Seals are found on the 

 wildest, most rocky, and least frequented coasts, 



