196 



THE SEALS. 



THE Amphibious Quadrupeds, properly so called, 

 compose a group of which, notwithstanding thv 

 pains that have lately been bestowed upon its eluci 

 dation, our knowledge is still in a very unsatis- 

 factory state. They are characterized by having 

 the feet formed for swimming, the toes being con- 

 nected by the skin, the hind feet expanded, and di- 

 rected backwards. The five species that have been 

 found on our coasts are referred to two genera, 

 Phoca >and Trichechus. In the former there are 

 six incisors above, four below; conical, curved ca- 

 nine teeth of moderate size ; five grinders on each 

 side, in both jaws, the anterior grinder with a single 

 root, the rest with two, all with a large conical, 

 compressed point, an anterior and a posterior pro- 

 minence, of which the latter is often two-lobed, 

 but which in one species are scarcely apparent. 

 The genus Trichechus is distinguished by the great 

 tusks in the upper jaw, and the absence of canine 

 teeth in the lower. In the young individuals of th 

 Walrus there are six incisors above, and four be- 

 low ; but these teeth fall out before the animal at- 

 tains maturity. The Seals of the British seas re- 

 mained in a great measure unknown to naturalists, 

 until the recent visit of Professor Nilsson to 

 England, when he found occasion to point out the 



