NATURAL HISTORY, 107 



" These fteales be hardly killed, unlesse a man dash out their 

 braines. In their sleepe they seem to lowe or bleat, and there- 

 upon they be called sea-calves," HOLLAND. 



331. In some of the species these hairs are jointed, and formed in a manner 

 fesembiing the antennae (feelers) of beetles. They have their roots in a sort at 

 cylindrical capsule, of horny consistency at the bottom, and meet there with some 

 small vesse.s connected with the muscles, and also with a fine membrane which 

 liaes tne whole of the internal surface. These bulbous roots of the bristles, 

 especially in the fine membrane with which they are lined, are closely connected 

 with many ramifications of nerves. 



332. Wliy are the nostrils of seals -made to close habitually ? 

 Because, as the amphibious habits of the seal require the nostrils 



to be sometimes open and at other times closed, an effort of the 

 animal must be required to produce one or other of these ends. 

 The natural state of the nostrils is to remain closed, and an e/ort 

 is required to open them when the seal reaches the air. 



The wisdom of this provision is evident : the animal hunts its 

 prey beneath the water, and its nostrils being closed by their own 

 exquisite machinery, the seal has no care concerning them while 

 capturing its food. But when the capture is completed, and the 

 animal has no more effort to make for that purpose, it returns to 

 the air, and bestows an effort upon the necessity for breathing. 



333. IVTiy are the eyes of seals very fully and peculiarly 

 developed ? 



Because it is by sight principally that they pursue their prey. 

 Their nostrils are necessarily closed when under water, so that they 

 probably have no sense of smell in that situation. Their ears are 

 also small, and become contracted under water ; the sense of sight 

 is therefore their chief guide. 



334, The eye of the seal is fitted for a double action, for seeing either in the water 

 or the air. There is no eye which can be said to have, upon the whole, to perform 

 these offices so equally. They have to use their eyes deep in the water, and when 

 there is very little light, or indeed none, the water being sometimes frozen over, 

 and a deep stratum of snow lying upon the ice. The eyes are placed very near to 

 each other, thus indicating that they follow their prey from a forward view. The 

 schlerotic coat is composed of a thick, hard, and firm membrane, by which strength 

 is given to the eye under the pressure of water ; and there is a provision for 

 adjusting the focus of sight to the dissimilar conditions of seeing in air and in 

 fluid. While, to modify the change, the cornea of the eye is flat, there being 

 less difference a ligbt from a flat cornea than from a convex one of the same 

 surface. 



