248 NATURAL HISTORY. 



a long, narrow snout, but 110 special crest on the summit of the head, and the blow-holes were situate 

 as in the foregoing three last-mentioned living genera. Van Beneden has given the following formula 

 of the dentition : Incisors, jj=| ; canines, ^ ; molars, J|=i| = 60. Their teeth in most respects re- 

 sembled those of the Zeuglodons. Much less is known of the PHOCODONS, our information regarding 

 them being chiefly derived from the teeth. These latter were not unlike the rearmost of those of the 

 Zeuglodons and Squalodons. The Zeuglodons have been found in the Eocene and Miocene strata of 

 North America. The first remains from Alabama were considered by Dr. Harlan to be those of an 

 enormous reptile (Basilosaurus), but Professor Owen proved their Mammalian character from the 

 teeth being implanted in distinct sockets. The Squalodons and the Phocodons have not only been 

 found in the United States, but in Australia, and in France, Belgium, Austria, Italy, and England. 

 Of course nothing is known respecting their habits other than what may be legitimately inferred 

 from their skeletal peculiarities. To all intents and purposes, so far as we know, the balance lies in 

 favour of their having had the habits of Whales. They may have been river-frequenters, and judging 

 from the dentition their food woiild be similar to that of the Ganges and Amazon Dolphins. 



THE RIVER DOLPHINS (PLATANISTID^). 



Three living forms come under this heading, which, however, barely present such characters in 

 common as to render them a compact group ; and some authorities even incline to regard them as 

 representative of sub-families. As in the Seal-toothed Whales their neck vertebrae are separate. 



THE Susu, OR GANGETIC DOLPHIN.* This remarkable Cetacean is never found in the salt water, 

 or at best only in the brackish water of the Sunderbunds ; its habitat being the rivers Ganges and 

 Indus from their mouths upwards, and their various tributaries almost to the mountain ranges in the 

 north. Specimens have been got at least 1,000 miles beyond Calcutta. It measures from six to 

 twelve feet in length, and in colour is entirely sooty black. Its long body has a moderate girth, and 

 just behind the middle of the back there is a slight elevation which can barely be called a fin. The 

 tail is broadish ; the flippers are short, very broad, fan-shaped, and not pointed as in most Whales. 

 The head is globular, with a long, narrow, spoon-shaped snout. The opening of the blow-hole, unlike 



that of other Whales, 

 excepting the Inia, is 

 not transverse, but a 

 single longitudinal slit. 

 The eye externally, 

 situated above the angle 

 of the mouth, is so 

 diminutive as barely to 

 be visible. We may 

 compare the Susu to the 

 Mole in this respect, for 

 in an adult eight feet 

 long the whole of the 

 eyeball is no bigger than 

 a pea in size. Small 

 though this eye is, 

 nevertheless it is perfect 

 in lens and humours, &c. 

 The ear-orifice behind 

 the latter may be com- 

 pared to a pin-hole. The 

 narrow rostrum of the 



upper and of the lower jaw is implanted with a series of teeth, more pointed and conical in front, and 

 narrower and laterally flattened in those behind. In the young animal the difference between the 



* Platanista ganc/etica. 



SHE (A) AND UPPER (B) VIEWS OF SKULL; (c) REARWARD AND (n) FORWARD TOOTH OF 

 YOUNG OF GANGETIC DOLPHIN. (After Gervais and Yan-Beneden.) 



