SEA-COWS. 
81 
are either absent, or simple square teeth with transverse ridges, 
suitable for chewing water-weeds and other vegetable substances. 
The opening of the nose, as in the Elephants, is placed far back 
on the upper surface of the skull. 
Of the living representatives of the group, the Manatees 
{Manatus) have about twenty molars on each side, of which six 
or eight are present at any one time. The muzzle is but little 
bent downwards ; the tail is depressed and rounded, with its 
hind edge forming a semicircle ; and there are rudimentary 
nails on the flippers. The Manatees, so called from their using 
their flippers to a slight extent as hands (unarms) ^ are natives 
of the rivers and shores of Eastern America and Western 
Africa within the tropics, never straying far out to sea, but yet 
unable to go on land, their whole lives being passed in the 
water. There are three species, namely the African M. sene- 
galensis, the American M. americamis, and the Amazonian 
AI. inunguis. 
Mounted specimens and skeletons of Alanatus munguis and 
AI. americanus are placed in the cases. 
The Dugongs, Halicore, represent a second genus, character- 
ized by the possession of two tusk-like incisors, and five or six 
molars on each side ; the snout is bent nearly vertically 
downwards, whiJe. there are no nails on the flippers ; and the 
tail is broad, wdth the hind edge nearly straight, somewhat as in 
Whales. Dugongs inhabit the coasts of the Indian Ocean, 
from the Red Sea to Australia, living in shallow waters, and 
feeding, like Manatees, on marine and river weeds, but being on 
the whole more marine in their habits, and taking more readily 
to deep water. Three species have been distinguished, namely, 
H. tabernaculi, the Red-Sea Dugong, B. dugong, the Indian, 
and H. australis, the Australian species. A specimen of the 
Red- Sea Dugong and a skeleton of the Indian species, as well 
as skulls, are exhibited. 
The Northern Sea-Cow {Rhytina gigas'), which formerly 
inhabited the shores of the islands in the neighbourhood of 
Bering Strait and Alaska in numbers, represents a genus with- 
out teeth, their place being taken by rough horny plates ; snout 
moderately bent downwards ; flippers short ; tail with two 
G 
