SEL VAS — DOLPHINS— BA TS 381 



of the aye-aye) was regarded as of no taxonomic importance, and consequently 

 the genus has been placed in the Polyprotodontia, and regarded as a specialised 

 relative of the American opossums. Selvas belong to a family (Epanorthidce) of 

 which the existence was first made known by the evidence of specimens from the 

 Tertiary deposits of Patagonia. Both species are very rare, and their habits are prac- 

 tically unknown. The larger species, known by the name of " raton runcho " in its 

 native country, lives in large forests, and is said to eat birds' eggs and small birds. 

 Fresh-water The larger rivers of South America are the habitat of two 



Dolphins. remarkable fresh-water dolphins belonging to a distinct family, the 

 Iniidte. One of these, the inia (Inia geoffroyensis), of the Amazon, has no 

 distinct back-fin, and attains a length of about 7 feet. The second, Pontoporia 

 blainvillei, which frequents the lower reaches of the Plate River, is much smaller, 

 and has a well-developed back-fin, and a sharper beak. In colour it is brown, 

 lighter below than above. The inia has from twenty-six to thirty-three pairs of 

 teeth, which show distinct tubercles at the inner sides of their crowns in the 

 posterior part of the series. A few hairs occur on the body. These dolphins are 

 commonly seen in pairs, and this fact, combined with their peculiar movements in 

 the water, makes them at once recognisable. When coining to the surface, the inia 

 first shows the crown of the head, after which it " spouts," and then descends 

 head-downwards, so as to show the back in what looks like a somersault. 



In addition to the foregoing, true dolphins occur in the larger 



True Dolphins. . ' , . . . 



South American rivers. Among these is the Amazonian tucuxi 



(Sotalia tucuxi), which differs from the inia in generally swimming about alone, 



and in showing its back-fin when rising to the surface. Besides the tucuxi, which 



is very common in the mouth of the Tocantins during the dry season, the Amazon 



is inhabited by another species, the pale river-dolphin (S. pallida), distinguished 



by the pale flesh colour of its back and tail-fin, and the white of its under-parts. 



Reverting to land mammals, some mention must be made of the 



Bats 



South American bats, of which a large proportion belong to the 

 vampire group. Among the typical bats a notable species is the tri-coloured bat 

 (Tltyroptera tricolor) of Brazil, which carries on the lower surface of the thumb, 

 as well as on the side of each foot, a disc-like sucker, for the purpose of enabling 

 it to cling to the smooth surfaces of trees and large leaves. This bat is further 

 distinguished by the possession of three joints to the middle finger. Its nearest 

 relative lives in Madagascar. Equally remarkable are the pouch- winged bats of 

 Central and South America, distinguished by a glandular pouch on or near the 

 elbow. One of these, the thin-tailed bat (Saccopteryx leptura), of British Guiana, 

 has a frill-like fold of skin which it can protrude from the gland-sac, the use of 

 which is as yet unknown. The white bat of Central and South America is remark- 

 able as being the only species of that colour, except albinos. This bat (Diclidurus 

 albus) is creamy white on the body and pure white on the wing-membranes, and 

 has a peculiar pouch between the legs on the under side of the membrane. 

 Another curious species is the hare-lipped bat {Noctilio leporinus), which takes its 

 name from the form of the muzzle, and eats cockroaches, sucks the bodies of small 

 birds, and catches not only fresh-water shrimps, but also small fishes. 



Another characteristic group is that of the mastiff-bats, distinguished by their 



