INTRODUCTION. 
IV. SYSTEMATIC. 
There can be few more difficult areas for a systematist to deal 
with than Malaysia, With its four large land-inasses, its high 
mountains, compact archipelagos, abundant coastal islands, and 
numerous oceanic islands, the division of species widely spread in 
the sub-region often calls for a nicety of judgment in which the 
personal element must, in the present state of ornithological practice, 
play a large part. Throughout the subregion, as elsewhere, the 
smaller islands show a relatively greater tendency to produce sub- 
species than do the large land masses. On the former the “biological 
discipline” seems less severe and variation is perpetuated : on the 
latter it is absorbed. In many cases the subspecies are ivell-defined 
the differences being qualitative rather than quantitative in character 
and in some instances the Javan and Bornean representatives of 
species also occuring on the' Continent are so well marked that only 
those workers, w'ho like myself take a very broad view of a “species”, 
would attempt to link them in a trinominal nomenclature. 
The Anamba Islands in the South China Sea present the reverse 
state of affairs. They are inhabited by continental, lowland species, 
but the insular forms usually diverge in the direction of slightly 
larger average size. On paper the distinctions seem insignificant, 
in birds the size of a bulbul sometimes only amounting to two or 
three millimetres on the mean, but to ignore such distinctions based 
on good series is to ignore one of the most important phenomena 
presented by the island avifauna. 
An even more delicate development of this situation is presented 
by some species in which a tendency to modification in the same 
direction is expressed, whenever a group is isolated, over a large 
geographic range. Aplonis is a case in point. On all the small 
islands of the South China Sea and its ramifications the glossy starling 
varies in the direction of large size and a more robust bill. The first 
name applied to these insular birds was based on specimens from the 
Anamba Islands, but as the same subspecifie characters are found in 
varying degrees on all small islands south to the coast of Sarawak 
and then along the east coast of Borneo the result is a race Ill-defined 
in range and characters. An interesting phenomenon bearing on the 
origin of subspecies may here be noticed. In Malaysia, where a 
section of a species is segregated it not infrequently throws up an 
individual in w’hich a subspecies seems to be adumbrated. Thus 
among sunbirds and fiowerpeckers living on coastal islands occasional 
individuals have relatively large bills, a character on which subspecies 
in these groups are often based; certain species in the Tioman and 
Rhio Archipelagos produce large individuals w r hich are approaching, 
or are inseparable from, large races of the species found in the remoter 
Anamba and Natuna Islands; and the large fruit-pigeon Ducula 
aenea , of which, in spite of large series, I cannot separate a Bornean 
subspecies, does occasionally show a very blue tail in that island. 
xvn 
