AMPHIBIOUS QUADRUPEDS. 263 



heart, from one of its chambers to the other, thus 

 passing from the veins directly into those vessels 

 that drive it through the whole frame. But the 

 moment the animal is brought forth, the passage 

 through the partition (which passage is called the 

 foramen ovale) closes up, and continues closed for 

 ever ; for the blood then takes its longest course 

 through the lungs to return to the other chamber 

 of the heart again. Now the seal's heart resem- 

 bles that of an infant in the womb, for the fora- 

 men ovale never closes ; and although the blood 

 of this animal commonly circulates through the 

 lungs, yet it can circulate without their assist- 

 ance, as was observed above, by a shorter way.* 

 From hence, therefore, we see the manner in 

 which this animal is adapted for continuing under 

 water ; for, being under no immediate necessity 

 of breathing, the vital motions are still carried on 

 while it continues at the bottom ; so that it can 

 pursue its prey in that element, and yet enjoy all 

 the delights and advantages of ours. 



The water is the seal's usual habitation, and 

 whatever fish it can catch its food. Though not 

 equal in instinct and cunning to some terrestrial 

 animals, it is greatly superior to the mute tenants 

 of that element in which it chiefly resides. Al- 

 though it can continue for several minutes under 

 water, yet it is not able, like fishes, to remain 

 there for any length of time ; and a seal may be 



* 1 have followed the usual observations of naturalists with respect to the 

 foramen ovalc in this animal : I have many reasons, however, to incline me 

 to think that the foramen is not entirely open. But this is not the place for 

 a critical inquiry of this kind. 



