178 MAMMALIA— ORDER VIII.—CETACEA. 



haunting fish, which are raked up from the mud by the long beak. The other 

 two existing members of the family are South American. One of these is 

 the inia or Amazonian dolphin (Inia geoffroyensis), inhabiting the upper 



portions of the river-system from 

 which it derives its name, and being 

 more porpoise-like in form than the 

 last. The long cylindrical beak has 

 a number of sparse bristly hairs; 

 and its numerous teeth have a 

 tubercle at the base. Unlike the 

 susu, the eye is fairly large, and the 

 flippers are not fan-shaped. Seven 

 feet is the maximum length of the 

 Fig. 95.-GANGETIC Dolphin ™al<^ ini^, ; and the general colour is 



(Platanista, ganyeiica). blackish above and reddish beneath. 



From both the preceding the small 

 La Plata dolphin (Stenodelphis UamviUei), from the estuary of the Rio de La 

 Plata, may be at once distinguished by its uniformly buff coloration, which is 

 admirably suited to harmonize with the colour of the stained water of the Plate 

 river, and at once proclaims that the species is not of pelagic habits. In size, 

 this dolphin seldom, if ever, exceeds 5 ft., and is often considerably less. 

 Unlike both the other species, it has a well-developed back-fin, and the beak 

 is of great length, and furnished on each side with from fifty to sixty teeth ; the 

 number in the other genera being about thirty. Another distinctive feature 

 is to be found in the form of the blow hole, which forms a transverse crescent, 

 instead of a longitudinal slit. At certain seasons of the year enormous 

 numbers of these elegant little cetaceans are captured in the Bay of Monte 

 Video by the fishermen, who detest them on account of the large quantities 

 of fish they consume. 



The whole of the remaining members of the order are included in the 

 single family Ddphmidce. The majority of the species are of comparatively 

 small size ; and while most are found in the neighbourhood 

 Porpoises, of coasts where they frequently ascend tidal rivers, a few are 

 Dolphins, etc. of exclusively fluviatile habits. Many of the genera are 

 very closely allied, and distinguished mainly by the structure 

 of the skull, so that in a popular work it is by no means easy to indicate their 

 distinctive peculiarities. While the majority resemble the PUtanistidce in 

 possessing a numerous series of teeth in each jaw, in two species this is not the 

 case. From that family they maybe distinguished by the shorter union between 

 the two branches of the lower jaw, and also by a difi'erence in the mode of 

 articulation of the ribs to the backbone. In all cases the blow hole is in the 

 form of a transverse crescent, with the two horns pointing forwards ; and 

 very generally from two to four of the anterior vertebrre of the neck are 

 welded together into a solid mass. One of the most aberrant, and at the 

 same time one of the most beautiful, members of the family is the spotted- 

 narwhal, or sea-unicorn (Monodon monoceros), the males of which carry the 

 well-known spirally-twisted "horn," or tusk, from which several of the 

 names of the species are derived. Exclusively confined to the Arctic seas, 

 where it associates in small "schools," the narwhal belongs to a group of 

 dolphins characterised by the blunt and rounded form of the head" and the 

 total absence of a beak. There is no back-fin ; the wide and rounded 

 flippers are short ; and the colour is dusky, with dark-grey mottlings. The 



