234 PINNIPEDIA. 



natural and well-marked sub -order of the Carnivora the 

 Pinnipedia of Illiger. They differ in many striking 

 characters from the families which we have already 

 considered, and it is highly interesting to observe the 

 various modifications of structure which combine to fit 

 them for their peculiar mode of life. The Bat in its 

 aerial flight, the Mole in its subterranean excavations, 

 and the Stag in his swift terrestrial course, do not 

 exhibit more perfect instances of the adaptation of form 

 and structure to habits than do these animals in their 

 amphibious existence. 



As already indicated, this group or sub-order may be 

 divided into three well-defined families, of which two 

 are represented in our fauna. Of these the first is that 

 of the typical Seals (Phocidce), of which the common 

 Ph. vitulina of our coasts may be taken as the type. 

 Here we have all the modifications of structure charac- 

 teristic of the group in their highest development. The 

 rounded head, the absence of an external ear, the 

 tapered almost spindle-form body, and the close-lying 

 outer hair, present no obstacle to a rapid passage 

 through the water, while the thick soft wool which 

 closely covers the skin prevents sudden changes of 

 temperature, and retains the heat of the body. A thick 

 layer of subcutaneous fat not only assists in promoting 

 the last object, but also renders the whole animal lighter, 

 and brings it nearer to the specific gravity of the fluid in 

 which it passes so much of its time. The eyes are large 

 and brilliant, and the nostrils are capable of being 

 entirely closed. The ears are inconspicuous openings, 

 totally devoid of any exterior conch, but provided with 

 a minute triangular valve which just closes the orifice 

 when submerged. The whiskers are very stiff and 

 thick, and appear to be of some importance as organs of 



