72 , MARINE AND AQUATIC TEESPASSERS. 



Crested Seal (Stemmatopus crestatus), so called on 

 account of the upper part of the head, which in the 

 male is developed into a sort of crest, that can be 

 raised or lowered at pleasure. It is, in fact, a modifi- 

 cation of the nose, and constructed in a singular 

 manner. 



An upright ridge of gristly substance passes from 

 the nose to over the top of the head, like the crest of 

 an ancient helmet, and averages some seven inches in 

 height. This supports the flexible sides of a large 

 pouch that communicates with the nostrils, and by 

 means of them can be inflated until it forms a large 

 projection on the top of the head, looking like a huge 

 wen. As soon as the Seal allows the air to pass 

 out of this singular structure, the sides collapse by 

 their own elasticity, so that in the course of a few 

 seconds the whole aspect of the animal is totally 

 changed. 



No one has the least idea as to the purpose which 

 this remarkable addition to the head is meant to per- 

 form. 



Some persons have suggested that, as the Seals are 

 very sensitive about the nostrils, and can be killed by 

 a comparatively slight blow at the end of the nose, the 

 inflatable sac is intended to protect the animal's life. 

 This object it certainly does fulfil, but I cannot think 

 that it was designed for any such purpose. 



In the first place, Seals were not made for the pur- 

 pose of being knocked on the nose ; and in the next 

 place, there can be no reason why the females and 

 immature males should not be endowed with the same 

 protective armour, their fur being quite as saleable as 



