WHALES AND DOLPHINS 



(CETACEA). 



Fish-likc carnivores waliuut hind-limbs, and having the fore-limbs converted into flippers, the tail in the form 

 of a horizontal fin. 'I'lie nostrils (blow -holes) are situated on the summit of the forehead, the ill-developed 

 lips arc without moustache hairs, the skin is naked, the placenta diffuse, and the teats situated far back in the 

 abdominal region. 



■<^3 



Sailors and the common people call these 

 giants of our present fauna simply " fishes," 

 and the form of the body is, in fact, exactly 

 that of a spindle-shaped fish, with a head, 

 often of enormous size, joined directly on to 

 the body without any apparent neck. Behind, 

 the body ends in a horizontal tail, which is 

 composed of a felt-work of horny fibres; while 

 that of the true fishes stands vertically, and 

 is supported by bony or cartilaginous rays. 

 Even the first superficial examination of a 

 living whale enables us to discover im- 

 mediately that the gills are altogether want- 

 ing; that these animals, although living in the 

 water, yet breathe atmospheric air; that they 

 have warm blood, and teats by means of 

 which they suckle their young. 



The skin, which is very thick, but composed 

 of a very loose or open tissue, has its meshes 

 filled with large quantities of fat, which also 

 collects between the skin and the muscles. 

 This skin is quite naked, the epidermis or 

 scarf-skin mostly thick and often like a rind. 

 Hair there is none. Only in the embryos 

 do we sometimes see traces of tactile hairs 

 on the upper lip, but these never cievelop. 

 The head may attain a third of the entire 

 length of the body; the brain-case is round, 

 but the jaws are drawn out in front into a 



^ Vol. II. 



sometimes broad, sometimes beak-like muzzle. 

 In the skeleton the prolongation of the jaws 

 forms a flat section, above which the back 

 part of the skull often rises in the form of a 

 crest, but in the living animal the space 

 between the brain-case and the snout is often 

 filled with large accumulations of fat or oil, 

 which gives the head a form quite different 

 from that of the skull. 



The structure of the respiratory passages, 

 the complete absence of external ears, and 

 the position of the very small eyes, so far 

 back and so low down, strike us immediately 

 on making a sufficiently close examination of 

 the form of the head. The nose is no longer 

 a smelling organ ; the whales are entirely 

 destitute of this sense. The olfactory nerve 

 is reduced to a thin thread. The nose is 

 now nothing more than a respiratory canal. 

 The nostrils open at the top of the skull, 

 sometimes through a single blow-hole in the 

 form of a half-moon, sometimes through two 

 contiguous slits. The cavity of the nose goes 

 vertically downwards, and its communication 

 with the windpipe is effected in a manner 

 quite peculiar. The larynx or anterior portion 

 of the windpipe, with the glottis or slit open- 

 ing into it, crosses the back part of the mouth, 



and fits into the lower end of the nasal passage 



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