of certain Birds of Cuba. 5 
has been swayed in no small degree by warmth of friendship,— 
perhaps, for this very reason, I am the more incapacitated from 
coming to any correct decision on the merits of his paper. I 
shall consequently say little on the subject ; except that, if any 
remarks of mine may have withdrawn his attention from the old 
method of first classifying organs or particular parts of structure, 
and then arranging animals according to this arbitrary division, 
and may have induced him, on the contrary, to consider the 
mode in which the structures of animals vary,—it must be con- 
fessed that he has developed, with reference to that mode, one 
class of animals much further than I have done. Birds now 
form the only class in zoology which has been arranged accord- 
ing to the variation of structure; that is to say, it is the only 
class of animals in which a naturalist has attempted, if I may be 
allowed the expression, to work out the place of every genus 
hitherto discovered. Every other class of animals, whether ver- 
tebrated or unvertebrated, requires still to be wrought out in a 
similar manner; and each genus not only to be placed with 
reference to its affinities and analogies, but, moreover, the rea- 
sons to be given in detail for this position. The great multi- 
tude of annulose forms that exist in nature, has given me small 
hope of ever being able to say that I know the natural position 
of every described genus in entomology; but I have endea- 
voured, both in the Hore Entomologice and in the first number 
of the Annulosa Javanica, to ascertain the place of some of the 
genera which constitute the natural group of Mandibulata,—a 
group of the same rank as that of birds. 
As to new views or principles in natural history, this mode of 
studying the variation of structure in different animals, in pre- 
ference to classing them according to an arbitrary division of 
organs, is perhaps the only one to which I can justly lay full 
claim. It is possible, indeed, that Hermann in his very remark- 
able 
