WHALES, PORPOISES, AND DOLPHINS. 177 



exclusively on squids and cuttle-fish. The bottle-noses, as typified by the 

 common Hyperoodon rostratus, so frequently stranded on the British coasts, 

 take their name from the extreme convexity of the crown of the head in the 

 adult male, which rises abruptly above the base of the short beak. They have 

 but a single pair of teeth in front of the lower jaw, but even these are in- 

 visible in the living state ; and the back, like that of the beaked-whales, 

 bears a fin. Although the common bottle-nose, which has a very wide 

 geographical distribution, does not exceed about 30 ft. in length, it is 

 valued not only on account of its oil, but likewise for the spermaceti con- 

 tained in the head. In addition to the large overhanging and unsymmetrical 

 crests above the nostrils, the skulls of old males have another pair of longi- 

 tudinal crests on the sides of the base of the beak, which come almost into 

 contact, and have their front surfaces broad, flat, and rugose. Cuvier's whale 

 {Choneziphius* cuvieri) difi'ers from the bottle-nose in possessing a pair of large 

 forwardly and upwardly directed teeth at the extremity of the lower jaw. 

 From both the preceding the beaked-whales (Mesoplodon) are readily dis- 

 tinguished by the production of the anterior portion of the skull into a long 

 cylindrical beak, composed of massive, ivory-like bone ; while they are further 

 characterised by the pair of lower teeth being generally situated near the 

 middle of the jaw. These teeth are generally of large size, and more or less 

 compressed latterly. In one species (Af. layardi) they are enormously 

 developed, and of a strap-like form, curving over the beak to such an ex- 

 tent as in some cases actually to prevent the mouth from being fully opened. 

 The beaked-whales appear to be solitary creatures, avoiding the neighbour- 

 hood of the coasts, and thus but seldom stranded. During the Pliocene epoch 

 they must, however, have been abundant in the English seas, as their solid 

 fossilised beaks are of common occurrence in the so-called crag deposits of the 

 -East Coast. Arnux's whale {Berardius arniixi), from the seas of New Zealand, 

 which is the last member of the family, differs from the true beaked-whales 

 in possessing two pairs of lower teeth. Whereas the beaked whales usually 

 measure about 15 or 16 ft. in length, this species reaches as much as 30 ft. 



A small family of the Odontoceti known as. the Platanislidw is represented 

 solely by three small species, two of which are exclusively freshwater, while 

 the third is an estuarine form. While resembling the 

 members of the next family in the possession of a numerous Freshwater- 

 series of teeth in both the upper and lower jaw, they are Dolphins, 

 distinguished by the length of the bony union between the 

 two branches of the latter, and likewise by the mode of articulation of the 

 ribs with the backbone. None of the vertebrae of the neck are welded 

 together. The typical member of the group is the well-known susu, or 

 Gangetic dolphin {Plalaiihta gangetica), which may often be seen sporting in 

 the Ganges, Indus, or Bramaputra. This species usually attains a length 

 of 7 or 8 ft., and is characterised by the long and compressed beak, in 

 which are crowded a very numerous series of sharply-pointed teeth, the 

 rudimental back-fin, the fan-shaped flippers, the slit-like form of the blow- 

 hole, and the minute size of the eye, which is perfectly useless as an organ 

 of vision. The skull may be recognised by the enormous curving longitudinal 

 crests arising from the base of the beak, and almost meeting above it. The 

 food of the susu appears to consist almost exclusively of prawns and bottom- 



* This name— originally applied to an allied fossil fonn — is used by Cope to replace 

 Zi]>hiMS,, on account of the pre-occupation of the latter. 

 13 



