The MALE differs in having the _head_ less conspicuously globose; the _cheeks_ less protuberant; the whole body more pilose, the anterior _spurs_ robust, short, and abruptly obliquely truncated; the _antennæ_ slender, filiform, much longer than in the female, but not much longer than the head, and from the fourth to the ninth joints serratulate within, adapting it to a sharp curve; the _abdomen_ being equal, cylindrical, retuse at its base, convex above, and flat on the venter, where it has a longitudinal deeply concave mucro in the centre of the second segment, which concavity runs along all the subsequent segments, and it is densely pilose on the fourth; the terminal dorsal segment being deeply emarginate in the centre and produced on each side into a broad obtuse process; the _claws_ are more robust than in the female and bidentate; the posterior pair being subclavate, and their single tooth abruptly reflected. NATIVE SPECIES. 1. _florisomne_, Linnæus, ♂♀. 3-5 lines. (Plate XIII. fig. 2 ♂♀.) _maxillosa_, Linnæus. _maxillosa_, Kirby. 2. _campanularum_, Kirby, ♂♀. 2-2½ lines. GENERAL OBSERVATIONS. These insects are named from _χηλὴ_, _a forceps_, and _στόμα_, _a mouth_,—in allusion to the forcipate form of the mandibles, which are strong, and cross each other in inaction. They and the next genus are styled _carpenter bees_, but they are not more consistently thus called than might be _Anthophora furcata_ and the genus _Ceratina_; they, in fact, like the latter, just as often avail themselves of an empty straw to form their cells in, or the cylinder that has been drilled by some xylophagous beetle of their own size, as they themselves drill into palings and solid wood for the purpose, but when they do this, it is facilitated to them by their powerful mandibles and their square and strong head. They are certainly very compactly formed, their structure being indicative of great power, of course relatively to their size. When they drill their cylinders themselves they are extremely persevering in its execution, and in the process, the material they extract, which is like fine sawdust, they withdraw from the depth of the cavity by passing it beneath them, and pushing it out at the orifice by means of their posterior legs and the apex of the abdomen, for they are too long to be able to turn within the cavity they have formed, its capacity not being sufficient to permit this, as it is very little larger in diameter than themselves. I have repeatedly watched them in these operations.