310 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 52. 



each side. The head bulges more or less behind the eyes, depending 

 on the species, and the whole hinder surface is cut out for about the 

 lower two-thirds of its length for the attachment to the thorax, and 

 principally for the reception of the elongated beak, which roughly 

 resembles that found in the long-tongued bees. 



The antennae are elongate, longer than the head and thorax, 

 slender, black in all maturely colored specimens, thickest at about 

 the fifth to seventh segments, tapermg apically to a point. The 

 number of segments found in the antennae varies from 35 to 45. The 

 first segment or scape (these two terms being used indiscriminately 

 in the specific descriptions) is small at its base, but much swollen 

 above and somewhat flattened, with the apical margin usually rounded 

 but produced into a small blunt tooth in one species. The second 

 segment is small and about the same diameter as the flagellum. Both 

 of these segments are smooth and shining and sparsely punctured 

 and hairy. The remaining segments of the flagellum are oyhndri- 

 cal, sHghtly constricted in their middle, dull, distinctly striate 

 longitudinally, and closely covered with short, stout, decumbent 

 hairs. The terminal segment is oval in shape with the apex pointed, 

 sometimes indistmctly separated from the preceding segment, and the 

 terminal segments show a more decided intersegmental constriction 

 than do the basal ones. 



The labrum is attached to the lower end of the clypeus in such 

 a way that it is slightly less prominent than the face. It is straight 

 in profile, but strongly arched transversely, and varies from distmctly 

 naiTOwer than long to slightly wider than long. Typically the whole 

 outline is curved from the narrow attachment at the top to the tip. 

 Sometimes the apical margm is nearly straight for a short distance on 

 each side of the middle fine, while in one species the sides appear 

 to be nearly straight for a little way, and usually the margins from 

 the rounded lateral sides to the attachment to the clypeus are straight 

 or almost straight. The lower border is more or less raised to form a 

 low marginal ridge which fades out on the sides. The whole surface 

 of the labrum is shuimg and usually smooth, although in many cases 

 the punctures are large enough to break up the smooth appearance. 

 The punctation, and with it the hairmess, is sparse, but the hau*s are 

 relatively long. The coloration is variable, although usually the same 

 as that of the face. The mandibles are strongly curved inward 

 near the apex, sharp pointed, and with a large tooth inside near the 

 tip. They are triangular m section near the middle, with the outer 

 side shghtly romided off and the base enlarged, while compared with 

 other members of the subfamily they are relatively narrow. Usually 

 they are pale except for the extreme tips, but in some species they are 

 wholly dark. 



