onkey;
Rheithrosciurus, a peculiar form of squirrel; and Trichys, a tailless
porcupine. These peculiar forms do not, however, imply that the separation
of the island from the continent is of very ancient date, for the country
is so vast and {377} so much of the once connecting land is covered with
water, that the amount of speciality is hardly, if at all, greater than
occurs in many continental areas of equal extent and remoteness. This will
be more evident if we consider that Borneo is as large as the Indo-Chinese
Peninsula, or as the Indian Peninsula south of Bombay, and if either of
these countries were separated from the continent by the submergence of the
whole area north of them as far as the Himalayas, they would be found to
contain quite as many peculiar genera and species as Borneo actually does
now. A more decisive test of the lapse of time since the separation took
place is to be found in the presence of a number of representative species
closely allied to those of the surrounding countries, such as the tailed
monkeys and the numerous squirrels. These relationships, however, are best
seen among the birds, which have been more thoroughly collected and more
carefully studied than the mammalia.

_Birds._--About 580 species of birds are now known to inhabit Borneo, of
which 420 species are land-birds.[88] One hundred and eight species are
supposed to be peculiar to the island, and of these one half have been
noted, either by Count Salvadori or Mr. Everett, as being either
representative species of, or closely allied to birds inhabiting other
islands or countries. The majority of these are, as might be expected,
allied to species inhabiting the surrounding countries, especially Sumatra,
the Malay Peninsula, or Java, a smaller number having their representative
forms in the Philippine Islands or Celebes. But there is another group of
eight species whose nearest allies are found in such remote lands as
Ceylon, North India, Burma, or China. These last have been indicated in the
following list by a double star (**) while those which are representative
of forms found in the immediately surrounding area, and are in many cases
very slightly differentiated from their allies, are indicated by a single
star (*). {378}

LIST OF BIRDS WHICH ARE SUPPOSED TO BE PECULIAR TO BORNEO.

TURDIDAE (Thrushes).

1. **Cettia oreophila.
2. *Merula seebohmi.
3. **Geocichla aurata.
4. **Myiophoneus borneensis.
5. Brac