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No. 1626. MAMMALS FROM HASTERN SUMATRA—LYON. 625 
and the natives told me that the “ Babi bakau,”’ Sus vittatus, was very rare. 
It is common everywhere on the mainland. 
On the small island of Pulo Payong, in the middle of Salat Rupat, the small 
pig, Sus vittatus, was very abundant, but Sws oi does not occur. The tracks. of 
tiger are said to occur occasionally on Payong, but the natives said they were 
not real tigers, but “ Rimau kwaka” (were tigers). 
Manis occurs on Bengkalis. No squirrel is found on Bengkalis, but Sciurus 
vittatus is plentiful across the narrow salat in Pulo Padang. No Ratufa occurs 
on any of the islands. 3 
The conclusion derived from the distribution of the mammalian fauna of 
these islands and of the Rhio-Linga Archipelago is that the present period is one 
of extension of land areas, either from elevation of land areas or more probably 
‘from alluvial deposit. The islands with hills have a much larger fauna. At 
some past period the islands in all this region extended to the mainland and re- 
ceived their fauna. Then followed a periad of depression, when everything was 
sunk below sea level, except the tops of the hills. These islands were small, 
too much so, for the larger mammals to continue to exist. ‘The squirrels, 
Manis, Tragulus, etc., remained on the small islands in safety. Then followed 
the present condition of things, elevation and alluvial deposition, enlarging the 
islands and extending the coast of Sumatra eastward and receiving additions 
to its fauna by Swimming and introduction by man. According to this theory, 
the islands of Rupat, Bengkalis, Padang [Merbau, Tebing Tinggi, Rengsam, 
and Penjalei] are of entirely recent formation and the present fauna has en- 
tered only comparatively recently.—W. L. Abbott. 
Doctor Abbott’s views as to the formation of these islands and 
the manner in which they received their fauna are entirely in 
accord with my own as based on study of his collections and of 
the elevations of the land and depths of the sea. His explanation 
of the manner in which animals may be carried from the highlands 
of Sumatra to the lowlands of the east coast may possibly explain 
some puzzling points noted beyond under 7ragulus (page 630), J/us 
(page 645), and Ratufa (page 636). 
Pulo Tebing Tinggt.—Also called Pulo Rantow. 
Pulo Merbau.—A small island. 
Pulo Rangsam (or Rangsang).——Also called Medang, but not to be 
confused with Pulo Medang off Pulo Rupat. 
The location and relative sizes of these islands may be seen on the 
map, page 623. They are all low alluvial islands, similar in general 
characteristics to the islands of Rupat, Bengkalis, and Padang, de- 
scribed above. 
Pulo Female (also called M endo!) .—This is a small alluvial island 
at the mouth of the Kampar River. 
Kateman River.—See map, page 623. 
The Kateman has a course of 25 or 30 miles through the low alluvial land 
of eastern Sumatra. The whole country is more or less swampy. No place 
is more than 2 feet above high water. There are many sago plantations along 
its banks. During the past five or ten years [this was written in the summer 
of 1903] much timber near the river banks has been cut by the Chinese for 
the Singapore market, but the lumbering operations never extend more than a 
