Body densely hirsute, spurs to
all the tibiæ - Bombus (26).
Body subpubescent, no spurs
to the posterior tibiæ - Apis (27).
It will be desirable to add a few observations to the preceding table to facilitate its use, and because, as many of the characters upon which it is framed are exclusively those of the female, it is necessary to point out the differences of their males, that the sexes of the genera may be duly recognized and associated.
It may be first noticed generally that the antennæ, in the males, are not usually geniculated at the scape, which is nearly always the case in the opposite sex, and they are also, with rare exceptions, always longer than those of their females. In Colletes, Prosopis, Dasypoda, Panurgus, Ceratina, Nomada, Melecta, Epeolus, Stelis, and Anthidium, the habit or colouring of the males is so similar to that of the females, that their genus may be thus at once determined, and, in fact, the brief characters in the table will embrace them.
The male Eucera can be distinguished from those of Anthophora and Saropoda, both by the differences in the number of the submarginal cells of the wing, and by the extreme length of its antennæ, whence the genus derives its name. In Andrena and Cilissa, the males have usually lanceolate bodies. In the latter genus there will be no difficulty in associating the legitimate partners; but in Andrena, although general habit will usually bring the male within the boundary of the genus, nothing but experience, or specific description will associate the sexes correctly, there being in many cases an extraordinary discrepancy between them. These two genera themselves also can scarcely be distinguished apart, excepting by means of their trophi; Cilissa, however, in general habit greatly resembles the genus Colletes, especially the Cilissa tricincta, which might, upon a superficial glance, be almost mistaken for one of them.
The male Halicti have long cylindrical bodies and long antennæ, but from the male Chelostoma, which has a very similarly shaped body also and long antennæ, they may be distinguished by the differences in the number of the submarginal cells; and from those of Sphecodes, by the antennæ, which, in the latter are not relatively so long, and are usually moniliform. The thorax of these is also less pubescent, and the tinge of the red colour of their abdomen is different from that of the red male Halicti.
The males of Cœlioxys can be readily distinguished from those of Megachile, by the spinose apex of their abdomen. In Megachile, general habit will bring the males within the precincts of their genus, as well as their largely dilated anterior tarsi in some of the species.