CRESTED SEAL. 201 



the optive nerve. This structure, by elongating 

 the axis of vision, may enable the animal more 

 clearly to discern distant objects, and also, by 

 the reverse, to draw the eye deep within the socket 

 during repose, especially as there are no moveable 

 eye-lids, but only the roembrana nictitans ; the lens 

 is spherical ; the iris is broad, and evidently mus- 

 cular." 



For the reason already assigned, we can sup- 

 ply little information from Dr Dekay himself. 

 Respecting the teeth, he remarks on one occasion, 

 " that they almost exactly correspond with those of 

 the Mitred Seal ;" and he says again, " the jaw teeth 

 are more closely approximated, the furrows in them 

 are deeper, and the last two are doubly furrowed." 

 " The dilatable sac," he remarks, " which comes 

 over its head, and which, when swollen up, appears 

 like bladders, is covered with short brown hair. 

 The opinion of the fishermen regarding this appen- 

 dage is, that it is a sort of reservoir for air, which 

 the animal uses when under water. Its great bulk, 

 however, when distended, would prevent the animal 

 from descending freely, or moving with facility be- 

 neath the surface of the water. The connection of 

 the nostrils with the hood, the configuration of this 

 part, and its internal structure, indicate its import- 

 ance as subsidiary to the sense of smell. The 

 weak arms of offence and defence allotted to this 

 animal render it necessary that this faculty should 

 be exercised in the greatest possible degree. The 

 hair of its hide is soft and long, and woolly under- 



