1909.) INSECTS OF THE “ SKEAT EXPEDITION.” 847 
the light; and I am sorry that I did not experiment with other 
flowers than those among which it was found. It would have been 
exceedingly difficult, if not impossible, to find any of sufficient size 
in the immediate neighbourhood of Kampong Aring. 
Hymenopus bicornis, the only representative of its genus, is 
an inseet which has a fairly wide dis‘ribation, being found in 
Sikkim, Java, and Sarawak ; but in none of these localities does 
it appear to be at all common; in Kelantan it is exceedingly rare. 
During the six weeks which the expedition spent at Aring, only 
One specimen was seen, though every clearing in the district was 
full of the blossoms of the Sendudok. It may be said that an 
animal so well able to hide itself might ea-ily exist in considerable 
numbers without being detected. This would have been perfectly 
true had the Mantis been in the habit of sitting still ; but move- 
ment in an apparent flower is just as attractive to a biologist 
as it isto alizard. After the first specimen had been captured, 
hundreds of bushes were examined with the very greatest care by 
three zoolugists and a botanist, but no Mymenopus was found. 
Granted that the insect is as highly specialized in instinct as it 
is in form—ani [ think there can be little doubt that this is 
the case—it is not difficult to suggest an explanation of its rarity. 
It is an animal which, for some reason, has had the greatest 
difficulty in holding its own in past ages, and it has been driven 
in the course of its struggle for existence to the extremes of 
specialization. It has become so highly speeialized, in fact, that it 
has condemned itself, as it were, to a single and very limited 
environinent ; and should that environment be changed, even to 
a slight extent, by external circumstances, the insect must either 
perish or alter both its structure and its habits immediately, a 
thing which no highly-specialized animal is likely to do rapidly. 
Now in the Malay Peninsula the conditions of life are always 
undergoing small changes that are apparent even to a traveller 
hastening through the country ; there must be many that years of 
research could not reveal. Suppose that the district of Aring 
were decimated by the small-pox, as many a Malayan district has 
been, and that the inhabitants who survived fled over into Pahang 
with their buffaloes, in a few years the jungle would kill off all 
the Sendudok bushes in the neighbourhood, for the plant can only 
exist in a clearing. In olden times, before the advent of the 
Malays into the Peninsula, the Sendudok must have been a rare 
plant in Kelantan, as neither the Sakais nor any of the other 
aboriginal tribes make clearings or keep cattle. The extremely 
local nature of the fruiting-season of various semi-cultivated trees, 
such as the Mangosteen (Garcinia mangostana), must have some 
influence on the insects of the different districts, and seems to 
depend not so much on local variations of climate as on the 
ditterent varieties of the trees that are popular in the different 
villages. One would like to know whether the variations of a 
fruit of such ancient cultivation as the banana affect the insects 
which liye upon it. In lower Siam over a hundred yarieties of 
(ela 
