( 23) 
It is seldom the case that one character, as we find it 
here, can be so extensively applied, and with so much pre- 
cision as to determine and separate all the genera of a de- 
finite group; it consequently makes the varying number of 
species congregated under each the more conspicuous, and 
we naturally ask, why are there so many of this peculiar 
structure here, or so few, or only one there? what object 
had nature in view? The fertility of some species also is 
remarkable, as compared with others. These are ques- 
tions which constantly recur, but when will they be an- 
swered? The variations of individuals can be more plau- 
sibly accounted for, but why is it more frequent in some 
species than in others? But so many questions can be 
asked in Natural History, and so few as yet satisfactorily 
answered, that I can only repeat what I have before 
urged, that, if every special fact be recorded when observed, 
time will do the rest, for nature is communicative at in- 
tervals only, and she must consequently be assiduously 
watched. 
Sc. 
I have enlarged above more than was perhaps desirable 
upon the differences of form in these insects, but some 
excuse may be found, possibly, in my wish to show that even 
in this small group there is much dissimilitude affording 
material for profound speculation and research, and that, 
consequently, whatever fragment we may pick up of the 
great book of nature, it becomes in the right minded, when 
diligently perused, the source and spring-head of a current 
of new thoughts, which, in their progressive development, 
deeply imbue us with the conviction that all is eoop, nothing 
has been created in vain; and that whatsoever of evil appa- 
rently exists, is to be found solely in our own moral turpitude 
