BLOWHOLE AND SPOUTING 



345 



to be seen on the throat. This is especially the case with the 

 Rorquals, in which group the Humpback Whale. Megaptera, is 

 to be included. The whales of 

 these two genera (Bcdaenoptera 

 and Megaptera) have a large num- 

 ber of the throat furrows as 

 many as sixty have been counted. 

 Some other Whales have a smaller 

 number ; thus Rhachianectes has 

 but two on each side, and the 

 Physeteridae have not many more. 

 These furrows are absent in very 

 young embryos. It is thought 

 by Professor Kiikenthal that they 

 allow of a wide opening of the 

 mouth. 



The blow-hole of Whales is, of 

 course, the aperture of the nostrils, 

 which are not so far back in the 

 foetus as in the adult. By the 

 characters of the nostrils the 

 Toothed Whales can be distin- 

 guished from the Baleen Whales ; 

 in the latter the orifice is double, 

 in the former single. In embryos 

 of Dolphins, however, the two aper- 

 tures are quite independent. The 

 phenomena of spouting have often 

 been misinterpreted. 1 When the 

 Whale breathes, the expired air 

 rushes out through the nostrils. 

 The water vapour in the breath 

 condenses into drops of water in 

 the cold Arctic regions where 

 the phenomenon has been mainly 

 observed. Hence the idea that water taken in at the mouth is 

 expelled through the blow-hole. As the Whale approaches the 

 surface to breathe, it may be that some of the water of the sea is 



1 "And at his gills draws in, and at his trunk spouts out, a sea," wrote Milton, 

 and think many others. 



JI 



FIG. 181. Dorsal surface of bones of 

 right anterior limb of Round-headed 

 Dolphin (Qlobicephalus mdas). x *fo. 

 The shaded portions of the digits 

 are cartilaginqus. c, Cuneiform ; H, 

 humerus ; I, lunar ; R, radius ; *, 

 scaphoid ; td, trapezoid or magnum ; 

 U, ulna ; u, unciform ; //- V, digits. 

 (From Flower's Osteology.) 



