114 MOSTLY MAMMALS 
Borneo, Java, Celebes, and Mindanao, together with some 
of the neighbouring islets, and are totally unknown to the 
eastward of the Molucca Sea. Although, being arboreal 
animals, it may be argued that, like the cuscuses of Celebes, 
they may have been carried about by floating timber, yet 
it seems in the highest degree unlikely they should have 
reached all the islands with an Oriental type of fauna and 
avoided all those where the true Australian type comes 
in. Moreover, they are very delicate animals, exceedingly 
difficult to keep alive in captivity, and there is accordingly 
a strong probability that they are native to the islands 
where they occur. Like so many of its other animals, the 
tarsier of Celebes is black—as, indeed, are the species 
from the other islands. 
So far, then, as their mammals are concerned, it seems 
probable that at no very distant epoch Celebes, Borneo, 
and the Philippines formed one land area; while Borneo 
itself was connected with the mainland, probably by way 
of Sumatra, the orang and some other species being common 
to these two islands and unknown elsewhere. It is further 
probable that Celebes, and most likely a portion of the 
Philippines, became isolated before Borneo ceased to be 
connected with Sumatra—or at all events with the main- 
land. Possibly this early separation may account for a 
very curious difference between the fresh-water fishes of 
the two areas; Celebes having no carps (Cyprinidae) or 
cat-fishes (Si/uridae), both of which are abundant in Borneo, 
as in Asia generally. With regard to the south-western 
portion of the Philippine group, it is important to notice 
that the island of Palawan shows evidence of a closer con- 
nection with Borneo than with the rest of the archipelago 
to which it belongs. On the other hand, the mountains 
of Luzon, in the Northern Philippines, are the home of 
