326 NITIDULID. 
believe, in Uruguay. In the tropical regions of America it is apparently extremely rich 
in species. Erichson! in 1843 described thirty-nine, and Reitter? in 1873 distinguished 
seventy-four. We have to record about fifty species from our region, a large majority 
of which are new. 
The specific characters have not yet been well defined; and I have experienced 
great difficulty in discriminating them in the material our editors have procured. 
This is chiefly owing to the very peculiar characters of the sexes: the males of many 
species differ greatly from the females in size, shape, and sculpture; and these sexual 
distinctions not only vary from species to species, but in some cases are inconstant 
even within the limits of a single species, the smaller males differing but little from 
the females, while the larger specimens of the sex in question may be so different in 
size and sculpture as to suggest at first that they belong altogether to another species. 
Therefore before attempting to determine the species the sexes should be distinguished. 
This can nearly always be done by an inspection of the apex of the hind body: the 
male has an internal supplementary segment, and though this cannot be itself detected 
in the normal state, yet its extremity is fringed with long hairs which can be perceived 
projecting externally between the dorsal and ventral plates of the last segment; usually, 
too, this sex has the hind margin of the last ventral plate depressed, and more densely 
ciliate than it is in the female; but this latter character must not be implicitly trusted, 
for in some species the females have these parts much more ciliated than usual, and in 
one or two even develop on the middle of the extremity of the last ventral plate some 
projecting hairs which look like the pubescence attached to the supplementary segment 
of the male. The true supplementary segment, or the extremity of the cedeagus, or 
both, are not infrequently a little extruded, and the individual may thus be distinguished 
as a male; but in the case of C. masculinus the female has a small chitinous process 
on the middle of the hind margin of the last ventral plate simulating the projecting 
apex of the male organs. In case of doubt existing as to the sex of an individual, a 
needle should be used, after the specimen has been softened, to separate the dorsal 
and ventral plates, and then the male supplementary segment, if the individual be of 
the male sex, will be detected closely attached to—in fact duplicating the edge of—the 
last dorsal plate. 
The female characters, so far as I have observed, are constant and without variation ; 
the most remarkable of the positive characters of this sex being a greater or less 
elongation of the wing-cases, with sinuation or prolongation of their apices; but this 
occurs only in a comparatively small number of species. 
As the species have been distinguished by previous writers chiefly by colour and 
sculpture, and as the former of these characters is apparently in some cases very 
variable, and as the latter is liable to great sexual variation in the male, it is almost 
impossible to determine with certainty from the descriptions what are the species to 
which they are intended to apply ; thus I have not ventured to identify by description 
