40 
that black is the highest coloui' development, then the species which 
has developed the least in its coloration is (Kvjijwda pallidida. This 
species is almost entirely testaceous, the only darkening that occurs is 
a patch about the 5th and Gth segments of the abdomen, and this 
showing only very slightly. In another species, O.nipoda soror, this 
coloured patch on abdomen is a little more marked, but otherwise the 
insect is coloured as in (Jxijpoda pallidida. This, then, seems to be 
the first stage in the development of alternate coloration. The next 
stage is shown by Oxypoda exolcta, which, in addition to having the 
patch on the abdomen dark, has also the head black. Still one more 
step, and in Oxijpoda alternam we have, in addition to the head and 
patch on the abdomen dark, the elytra dark as Avell; as a corrobora¬ 
tion that this is the correct order of development, it is curious to note 
that, at all events among the British members of the genus, aU those 
which have the head dark have the patch on the hind-body dark, and 
that all those which have the elytra dark have the head and the patch 
on the hind-body dark as well. These facts seem to point to the i)ast 
history of the group in a very marked manner. That originally the 
family started from a very pale species whose development as regards 
coloration was very slight after emergence from the pupa; the next 
stage reached was the development of darker coloration near the 
extremity of the abdomen ; a stage further the head becomes dark, and 
then the elytra become dark, giving the characteristic alternate colora¬ 
tion so widely scattered throughout the Avhole family ; beyond this point 
many alterations in the coloration are made, some becoming entirely 
black and others with lighter elytra, some with pale heads, some with 
darker legs ; in fact, every description of colour arrangement can be 
illustrated by some species or other. 
As, perhaps, throwing a further light on the life-history of the 
group, I may mention that out of the 11 alternately-coloured species 
enumerated, nine are found in fungus; the only ones not found in 
fungus are the four species of I’acdvnia and IhijitoUnitfi oltcnunn^, and 
even this latter is found under rotten bark which generally has a 
fungoid growth on it. Here, for the present, I must leave this most 
interesting side of the question. 
Having now shown briefly the way in which coloration assists us 
in obtaining some knowledge of the past history of a group, I will now 
draw your attention to the varied results of coloration as bearing on the 
life-history and existence of the individual insect. No one, having 
read Darwin’s and Wallace’s books on this side of the question, can 
doubt the importance to the insect of coloration suitable to its habits 
and environment, and it is more to the special instances rather than 
the importance of the result that 1 wish to draw your attention. The 
main end of colour is to assist in prolonging tlio life of the owner, and 
with our British Coleoptera in by far the largest number of instances 
this is achieved by the insects being coloured black, that l)eing best 
suited to the nocturnal habits of the species. There are, however, 
usually a few species amongst our nocturnal genera that during tlieir 
evolutionary history have changed their habits and have become diurnal, 
and when this is the case their coloration alters almost invariably, 
'riiat this should be so is not, of course, surprising, as it is easy to 
understand that a black colour as a protection by night is by no means 
so by day, except unde)’ certain circumstances, and so we iind that oui’ 
diurnal beetles with black antecedents continue to make a dillerent 
