INTRODUCTION. 
In these species it would seem that isolation and the correlated un- 
checked variation is a more important factor in the evolution of new 
forms than adaptation to a peculiar environment. 
In this list a very broad view of a ' ‘species* * is taken and there 
is an extensive linking of geographical races and representatives in 
the German fashion as I feel that in this way the specific names can 
usefully be given a secondary function to express relationship. Many 
of the combinations adopted are novel. Fo^ instance, the monotypic 
Bornean genus Allocotops is reduced to the rank of a subspecies of 
Melanocichla. lugubris and the rather distinct j?htytdura phoenicura 
of Java becomes R. perlata phoenicura , In the opposite direction 
species are split down to the lowest possible limit and many of the 
subspecies accepted are based on very fine distinctions. In the matter 
of genera I have been very conservative and have "lumped" exten- 
sively, for I cannot yet appreciate, among birds, any natural generic 
criterion and have therefore employed the genus merely as a chapter- 
heading. Perhaps the views of the advocates of the small genus, 
even though the implication is the creation of a large number of 
monotypic genera, are more logical for, on a superficial survey, there 
does seem a point below which some groups of species seem indi- 
visible e.g. the more typical Zosterops , but consideration of this seems 
best left to workers with cosmopolitan collections at their disposal. 
The day is probably not far distant when the systematist will 
extend the present system of trinommal nomenclature to embrace, 
for want of a better term, antediluvian representatives, or in other 
words to recognize among existing species, subspecies in time as well 
as in space. That such is the relationship’ between numerous groups 
of closely allied forms now found distributed over the same territory 
seems very probable. Anthreptes malacensis and A . rhodolaema; 
and A e git kina tiphia and A. viridissima are two such pairs. In each, 
the first named species is commoner than the second, more wide 
spread in Malaysia, has developed more subspecies, and is more 
adaptable in the matter of terrain being found commonly in cultivated 
areas. It shows, in fact, all the manifestations one would expect 
an older stock to show in relation to a later wave of immigrants. 
Physiological intolerance must here play a part. A system of 
nomenclature exemplified by Anthreptes malacensis f rhodoltema] now 
suggests itself, but at this point I hasten to add that the system has 
not been adopted in this list. 
& * * $ * * 
If in the following pages it is found that some names and views 
do not agree with those in papers previously published it must be 
remembered that opinions often alter as new material accumulates. 
Our former method of work was to write reports on general collections 
from specified localities. Although such papers are, primarily, of 
interest to the zoo-geographer and the famiist the method has its 
disadvantage from the systematises point of view for there is always 
xviii 
