THE ZooLocist—Januanry, 1872. 2879 
This idea is obviously that of the field naturalist rather than the closet 
naturalist, the out-of-doors student rather than the book-worm. 
ili. The eclectic idea: the idea that the study of the imago and 
the study of the larva should be intermixed and their characters com- 
bined into one harmonious whole: this idea was that of Latreille 
and Boisduval. This system has been explained and adopted 
by Mr. Westwood, in his ‘Modern Classification,’ and adopted in 
a concise but very explicit manner by Mr. Stainton, in his ‘ Manual 
of British Butterflies and Moths,’ and has been reduced to prac- 
tice by Dr. Staudinger, in his ‘ Catalog der Lepidopteren,’ a most 
laborious compilation, now in the hands of every European Lepi- 
dopterist. This system has its obvious advantages, for whereas 
the first regards the butterfly as a lay figure set up and postured, 
and the second regards it before it has attained half its attributes, 
the third treats it as a progressive history gradually unfolding itself, 
and to make that history complete you have to study it con- 
tinuously, not only when wearing the imperial purple but when 
struggling and toiling for a mere existence. But as entomologists 
are not all statesmen, and therefore some may fail to appreciate this 
illustration, I will borrow another from commercial usage: those 
tradesmen who would prove beyond question the truthfulness of 
their books and the reality of their position, keep their books bya 
system of double entry; and the accounts are thus made to verify 
themselves, or at least furnish ready means of detecting error: 
now there can be no question that structure presents us with a 
series of natural differences which may be useful to us in forming 
a classification; for instance, some butterflies are invariably pro- 
vided with six legs, all of which are formed alike, and all perfectly 
adapted for walking: others have but four such legs, and in lieu of 
the anterior pair of perfect legs have a pair of imperfect legs quite 
incapable of performing the usual function of legs, progressive 
motion ; hence these two sections of butterflies have been denomi- 
nated “hexapod,” or six-legged, and “ tetrapod,” or four-legged : 
this offers us one mode of keeping our accounts with the butter- 
fly world. It is equally a matter of certainty that a constant 
difference obtains in the economy of the living insects, some of 
them turning to a chrysalis supported by a belt passing round the 
waist or middle of the body, and so remaining fixed with the head 
upwards, and others attaching themselves by the tail and hanging 
head downwards. Here we have characters for two systems of 
