178 
gradually turns life and habits into a new channel. There are 
other cases in which structure is found to vary, while the 
surroundings—so far as we see—remain exactly as before. Or 
under apparently the very same conditions, we occasionally meet 
with variations, the same in kind as well as amount, in two quite 
distinct organs, in two different but closely allied species. This 
last circumstance is a very remarkable one, and it bears directly 
upon the case before us. The Longicorn Beetle exhibited, which 
has led us to these considerations as to structure and its 
variations, is distinguished by its extraordinarily Jong antenne, 
and we can only conjecture what may be their use. Now it is a 
singular fact that in another species of the same Linnean genus 
Cerambyx found in South America, C. longimanus, while the 
antennz are not more developed than usual in that family, the 
first pair of legs in this insect are so astonishingly lengthened out 
as to be in utter disproportion with all its other measurements.* 
De Geer considers the Cerambyx longimanus as one of the largest 
and most remarkable species of that genus in the world. The 
body is two inches and a half long, and the first pair of legs is 
sometimes double the length of the body, while the other pairs of 
legs are of the usual proportions. It is also noticeable that 
in this insect also, as in C. edilis, this abnormal development is 
confined chiefly to the males. I have suggested a use to which 
possibly the long antennz of the male C. wdilis may be put; and 
whatever that use may be, we might well suppose the long fore 
legs of the C. longimanus to have a similar use. The variations in 
the two cases are analogous, though showing themselves in 
different organs. But supposing it so, who can give a reason 
why a pair of very long fore legs should be selected in one 
insect to perform the same function as a pair of very long antenne 
*See'a figure of Cerambyx longimanus in Shaw’s Naturalists’ 
Miscellany, vol. 4, pl. 184. There is also a remarkably fine specimen of 
the insect itself in the Museum of the Bath Literary and Scientific 
Institution. 
a 
