Stephens, J. F. 1829b. A systematic catalogue of British

INTRODUCTION. XIU
quilius (Syst. Nat. ii. 558.—Faun. Suec No. 397.), and the female
Coccinella ! unipunctata (Syst. Nat. ii. 579.—Faun. Suec. No. 470.)
which is the more to be wondered at, as, from the insect being far
from uncommon in Sweden, he might have had frequent oppor-
tunities of detecting the identity of the sexes. But in the instance
noticed from Mr. MacLeay, the insect in question is a native
of South America, and consequently the writer had no means of
ascertaining any portion of its history, but was subsequently in-
debted to the observations of Mr. Swainson, whose zeal for entomology
led him to explore the distant region of Brazil, for correct-
ing the mistake into which he had accidentally fallen *. But as
I have elsewhere advocated the expediency of generic division, I
shall proceed to give some cursory observations upon species, and
upon the difficulty of discriminating them. It cannot be denied that
much obscurity prevails upon these subjects : it therefore becomes
the duty of every inquirer to endeavour to dispel the mist, and to
contribute his mite towards their elucidation; though I do not
assume that such should be the sole object of every one. I would
rather that attention should be paid to the economy, &c. of the
interesting objects of the entomologist's research; though I would
ask, how can an individual communicate to others the knowledge
he has acquired by his observations, unless he be able to define with
accuracy the very animal which furnished it ? Upon this con-
sideration, therefore, it is manifest tbat an examination into the
true distinctive characters of species should occupy at least a portion
of his time, instead of devoting it almost exclusively to searching
after the relationship ofaffinities,—which has been so much insisted
on by late writers, almost to the total exclusion of specific investi-
gation ;
or in generalizing upon structure before he is acquainted
with particulars.
In pursuing this investigation, the firstquestion which presents
itself is. In what do the characteristics of a species consist ? I need
scarcely add, that its solution is one of the utmost difficulty, as the
characters of many species are very obscure, and are not readily
detected, owing to the innumerable variations to which they are
subject from age, locality, or climate, or from the close approxima-
tion of those in kindred species. Of the latter description, the
genus CucuUia (part ii. p. 102.) offers a remarkable example; most
of the species of which it is composed resembling each other so
closely in their final state, that were it not from a knowledge of them
during their previous appearance (their larviE being totally dissimilar,
and their food and time of flight very different), they might
* A more recent example, however, occurs in a work which assumes
superior accuracy in the generic distribution of insects; in which the Musca
putris of Linne is converted into three species belonging to two genera.
Vide part ii. p. 319. Nos. 9126 and 9140.
;