36 MARINE AND AQUATfC TRESPASSERS. 



with the whale the case is exactly reversed. The 

 external orifice is, as we have seen, extremely small ; 

 but the eustachian tube is very large. This tube 

 opens into the nostrils, or blow-holes, just behind the 

 valve that keeps out the water; so that when the 

 animal rises to the surface, and the passage of the 

 nostrils is opened, the whale is able to hear atmo- 

 spheric sounds through the eustachian tube. Thus, 

 the creature is doubly armed : its tiny external ear 

 conveying sounds that are transmitted through the 

 water ; and its large eustachian tube receiving those 

 that are conveyed through the air. 



As for the sense of smell, it appears to be totally 

 absent, and this for two reasons. In the first place, it 

 would be impossible for the animal to use the sense of 

 smell while below the surface, unless, as Mr. R. Jones 

 tersely puts the case, " it had the nose of a fish, which 

 could not be granted without infringing upon the laws 

 that regulate the progression of animal organization." 

 When the creature is at the surface of the water, the 

 sense of smell is not needed, and, as has been men- 

 tioned, the nostrils are required for another purpose 

 namely, that of respiration, and are so filled with water 

 that no scent could reach them through the air. 



The foregoing remarks have been based upon one 

 species, the Spermaceti Whale. Reverting for a short 

 time to some of the structures which have been briefly 

 sketched, we shall see how they are further modified 

 in another species of the cetacea, a perfect water tres- 

 passer. 



The great Greenland, or right whale, which in- 

 habits the Northern seas, has most of the habits which 



