conica, Curtis, viii. 349.
Sponsa, Smith, ♂.
3. umbrina, Smith, ♂ ♀.
4. rufescens, St. Fargeau, ♂. 4-6 lines.
5. vectis, Curtis, ♂ ♀. 5-6 lines. ([Plate XII.] fig. 1 ♂ ♀)
6. inermis, Kirby.
GENERAL OBSERVATIONS.
This genus is named from κοιλία, belly, ὀξὺς, acute, in application to the conical abdomen of the female. The insects of this genus are parasitical upon the genera Megachile and Saropoda. Thus, C. simplex infests M. circumcincta; C. rufescens, M. Willughbiella; C. vectis, M. maritima; and C. umbrina is parasitical on Saropoda bimaculata. Linnæus, from the different appearance of the two sexes made two species of them, and from the circumstance of his having described first the male as Apis quadridentata, this, by the law of priority, supersedes the name of C. conica as the name of the species, which is its female, and which he next described, and thus that sex, whose form Latreille adopted as typical of the genus, is in the series of species totally superseded and reduced to a synonym. The species of this genus are extremely difficult to separate from each other, no tangible character presenting itself conspicuously, although the Swedish entomologist Nylander supposes he has found one in the plates of the apical segment of the abdomen, especially those of the venter, in which he detects both a difference of form and a difference of relative length to that of the superior plates, and in the males he assumes that the teeth of the apical segment are constant characters. Not having had sufficient opportunity since this supposed discovery was made, for the examination of a great multitude of specimens, for it is only upon such an investigation that it can be firmly based, I cannot speak corroboratively upon the point, but it is very possibly a correct solution of the difficulty.
The peculiarity of these spines at the apical segments of the abdomen of the males is remarkable, they being straight projecting processes, or they have even a slight upward bearing. In the males of Anthidium and Osmia we observe spines also arming the apex of the last segment, but in these we can trace an evident use, both from the downward curvature of the abdomen itself, and that same tendency also in the spines. But in the insects of this genus they have not the same conspicuously apparent object, the abdomen itself even having an upward curvature, or rather a greater facility for turning upwards than downwards. These insects appear to be most abundant in the midland and southern counties, and, according to Curtis, they are numerously found at the back of the Isle of Wight. I have usually taken them on the wing and never on a flower, and I do not know the plants which they may prefer.