334 WHALES AND DOLPHINS 



Sotalia resembles the Bottle-nosed Dolphin, Tursiops, and 

 the Rough-toothed Dolphin, Steno, but is distinguished from 

 them, among other features, by the backbone having 10 to 15 

 less vertebrae and, more obviously, by the increased number of 

 teeth, the number in Sotalia ranging from 26 to 35, whereas in 

 Steno and Tursiops it is 20 to 27. 



Sotalia species do not reach a large size ; they are none of 

 them conspicuously coloured, grey of various shades and white 

 predominating. The beak is long and distinct, and the dorsal 

 fin usually has a concave posterior border. Flippers are 

 recurved and distinctly broad at the base. 



The first three species to be described are ail from the 

 Amazon. 



Sotalia pallida, the " Buffeo bianco " of the missionaries of 

 the. upper Amazon, is a little dolphin about 5 feet 5 inches 

 long, yellowish white above, white below, with triangular 

 dorsal fin and 30 or 31 teeth on each side of upper and lower 

 jaws. It is recorded from Nauta, Peru, a distance of over 

 1600 miles from the mouth of the Amazon. 



Sotalia fluviatilis, the " Buffeo negro " of the missionaries, is 

 smaller than the preceding species, 3 feet 7 inches being a 

 recorded length. Its colour is dark grey on the back and 

 pinkish on the under surface. A broad band of dark colour 

 extends obliquely upwards from the dark-coloured flipper and 

 merges with the black of the back. Behind the eye the light 

 ventral colouring invades the dorsal black in a rounded tongue- 

 shaped projection. Teeth number 28 in each row. This 

 species is seen in troops of twenty or thirty, and is said to 

 attack the Bouto, the River Dolphin Inia. It is recorded 

 from the upper Amazon near Pebas, Peru. 



The Tucuxi, Sotalia tucuxi, was given its common name by 

 the natives of the upper Amazon. It is sombre, dark blackish 

 in colour. Teeth number 30 in each row. 



It is not quite certain whether the three forms just mentioned 

 are separate, or are only colour variations of a single species. 



Sotalia guianensis is found on the north-east coast of South 

 America. It is black or brown on the back and white under- 

 neath, and but for the typical Sotalia body form — long beak, 

 falcate dorsal fin and broadened flipper — there is no outstanding 

 feature by which to distinguish it. It is the dolphin commonly 



