FER^E. 



OF SEALS IN GENERAL. 



THE Seals are entirely marine animals, none of 

 the species having been hitherto mentioned as in- 

 habiting Tresh waters ; and they are the only a'ni- 

 mals, amongst the viviparous quadrupeds., which 

 can with propriety be considered as amphibious. 

 In all others the orifice, denominated by anatomists 

 foramen ovale, of the heart, which permits the foetus 

 to live in the womb without respiration, is shut 

 from the moment they come into the world, and 

 remains closed during their whole life. In the 

 Seals, on the contrary, this continues open, al- 

 though the mother invariably brings forth her 

 young ones on land, and their respiration com- 

 mences and operates, as in other animals, immedi- 

 ately after the birth. By means of this aperture 

 in the septum, which allows a communication of 

 the blood of the vena cava, and the aorta, these 

 animals have the advantage of occasionally sus- 



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