156 
Steller recognized the similarity of the sea-cow of the North 
Pacific to certain other animals already known ; but, being possessed of 
imperfect information, he assumed that all these belonged to a single 
species. We now know that this was an erroneous conclusion, that this 
sea-cow was specifically and generically distinct from others of the 
group, and it is consequently very often known as Steller's sea-cow. 
The sea-cows in fact form a peculiar group of the mammalia, which 
is now classed as a separate order and which shows little affinity to any 
other mammals, for though in its aquatic habits and in some other 
respects it resembles the whales and porpoises it is very different from 
these in anatomical structure. This is probably a very ancient group, for 
fossil remains referable to it are found in several geological formations 
in Europe, Africa and America ; but in human times it appears to have 
dwindled, and to be verging on extinction from natural causes altogether 
apart from any specific attacks by man. 
Within the historic period, this whole order of mammals has had 
but three living genera. The Manatee proper, which inhabits the 
shores and estuaries of the Atlantic within the tropics. The Halicore 
orDugong, found in the Red Sea, on the East Coast of Africa and in 
the Indian Seas as far east as Australia ; and the Rhytina, of which but 
one species ( R. Stelleri) appears to have existed. The last-mentioned 
is the sea-cow here specially referred to, that of the North Pacific. 
It is very often the case, that ancient types of animals which have 
already played their part in the history of the world, are found in the 
last stages surviving in a few forms widely separated geographically. It 
is so in the present instance. The Halicore is separated by the length 
of the African continent from the Manatee of the Atlantic, while 
Steller's sea-cow was discovered, as we have seen, on a remote island 
of the North Pacific. 
Early navigators had observed the Halicore and Manatee as 
animals of a strange and problematical character, and it is supposed that 
the habit of these animnis in carrying the young under the fore limb 
may have given origin to the fabled mermaid. Thus when systematic 
names began to be applied by naturalists, those animals belonging to 
this order were designated Sirenia. 
