concealing its divisions; _prothorax_ inconspicuous; _mesothorax_ convex, subglabrous on the disk; _scutellum_, lunulate, convex; _metathorax_ truncated; wings with two submarginal cells, the commencement of a third slightly indicated, the two complete ones nearly equal, the second of which receives both the recurrent nervures, one towards each extremity; _legs_ robust, very setose; the posterior _tibiæ_ slightly curved longitudinally, concavo-convex, broad at the extremity; all the _plantæ_ as long as their tibiæ and as broad at the base but decreasing at the apex to the width of the following tarsal joints, the anterior pair fimbriated externally, and the posterior pair clothed, on the inner surface, with a dense, short brush, the three following joints short, subequal, the claw-joint as long as the three, and the _claws_ with a broad basal inner tooth. ABDOMEN ovate, with parallel sides, convex above, truncated and concave at its base to fit the metathorax, distended horizontally in length, or with an upward curve, the four first segments slightly constricted, and their edges usually clothed with decumbent down; the terminal segment obtusely pointed and slightly depressed transversely towards its extremity; the _ventral segments_ commencing with the second, clothed with parallel layers of moderately long, straight setæ, which in each parallel are of equal length, but those on the fifth segment are the shortest, upon all of which the insect conveys the pollen it collects. The FEMALES of the second division of the genus scarcely differ. The MALES of the first division differ in having the _head_ slightly larger and squarer above; the _antennæ_ very slightly longer; the _mandibles_ more acutely tridentate, with a distinct powerful basal tooth beneath, terminating the concavity of the organ; the anterior _femora_, _tibiæ_, and joints of their _tarsi_, excepting the terminal one, concavo-convex, the four first joints of the latter distended laterally, and edged with a dense fringe of setæ, the distension of these joints is widest at their articulation with the tibiæ and they decline in length to the claw-joint which is long; the _claws_ bifid; the interior claw acute, but remote from the apical one; the posterior _femora_ are very robust, their _tibiæ_, much curved, robust, almost triangular, and externally very convex; their _plantæ_, almost glabrous, not so long as the three following joints, externally rather twisted, and beneath furnished with a dense brush of long stiff hair. In the second division of the genus the males are destitute of the distension of the anterior tarsi, these being instead densely fimbriated externally; the legs in them are much less robust, and more closely resemble those of their females. NATIVE SPECIES. § _Anterior tarsi of males much dilated._