CETACEANS. 157 



its base. Whether it be wielded in sportive mood or 

 in anger, its action is marked by rapidity and ease ; and 

 when struck forcibly on the surface of the ocean, it 

 produces a report which may be heard at a considerable 

 distance. In progression, the action of this organ is 

 precisely the reverse of that of the tail of the lobster ; 

 for, whilst the latter animal sw r ims backward, by 

 striking the water with its tail from behind forwards, 

 the Cachalot, and other cetaceans, swim forward, by 

 striking with their flukes in the contrary direction ; the 

 fin being brought beneath the body by an oblique and 

 unresisting movement, while the act of springing it back, 

 and straightening the tail, propels the animal ahead, 

 with an undulating or leaping gait. When employed 

 offensively, as in striking at a boat, the tail is curved in 

 a direction contrary to that of the object aimed at ; and 

 the blow is inflicted by the force of the recoil. 



The eyes are placed far back in the head, above and 

 between the pectoral fin and angle of the mouth : their 

 situation being chiefly denoted by a prominence of the 

 surrounding integuments. The aperture for vision is 

 not larger than two inches in its longitudinal, and one 

 in its vertical, diameter. The eyelids have neither eye- 

 lashes nor tarsal cartilages, but are otherwise complete 

 in the structures which adapt them for their office, and 

 are quite unencumbered by oil or fat. In the deacl 

 whale they are usually closed ; and in the living animal 

 they exhibit the phenomenon of winking. At the 

 inner angle of the eye, the conjunctiva forms a thick 

 duplicature, or rudimental third eyelid, of semilunar 

 form, and in appearance closely resembling the " haw" 

 in the eye of a horse. The eyeball is not a perfect 

 sphere : its anterior and posterior surfaces being much 

 flattened. It is deeply set within the lids, and chiefly 



