184 AMERICAN HYMENOPTERA. 



the Hymenoptera into superfamilies. I do not consider that 

 they should be given even separate subfamily rank. 



May I here cite the relationship of two other genera, as ex- 

 pressed in Dalla Torre's and Ashmead's classification, in sup- 

 port of my belief that Bombus and Psithyrus should be placed 

 in the same family ? Both Friese and Dalla Torre placed 

 the genera Melipona and Apis together in the subfamily 

 Apinse, and Ashmead included them both in the family Apidae 

 (in the restricted sense). To be sure, in their habits the spe- 

 cies of Melipona are more like those of Apis than those of 

 Psithyrus appear to be like those of Bombus, but Psithyrus is 

 structurally far more like Bombus than is Melipona like Apis, 



Centris and Eucera are evidently, from their structure, much 

 less closely related than are Bombus and Psithyrus, yet Ash- 

 mead did not consider it necessary to place them in separate 

 groups of subfamily rank in the family Anthophoridae, neither 

 did Dalla Torre place them in separate subfamilies of the 

 great family Apidse. I might cite numerous other examples 

 showing the inconsistency in placing Bombus and Psithyrus 

 either in separate families or in separate subfamilies. Those 

 who have so placed them have evidently been led to do so 

 by the general differences in habit between the two genera 

 rather than by structural differences. 



Characters on the Bombid^. 

 The family Bombidse, as extended to include Psithyrus, 

 may be briefly described as follows : 



Medium to large, robust bees with oblong bodies and a rather dense 

 covering of hair. Head subtriangular. Antennse geniculated, filiform, 

 longer than the head. Ocelli placed in a slight curve on the vertex. 

 Malar space (except in some males) ample. Clypeus not carinate. 

 The tongue long and slender, reaching considerably beyond the 

 propodeum when fully extended ; the labial palpi four segmented and 

 the maxillary palpi normally two segmented. Labrum transverse. 

 Mandibles of female stout, and grooved exteriorly towards their apex ; 

 those of the male two-toothed and heavily bearded exteriorly on 

 their lower sides. Front wings large (these insects are capable of long 

 and rapid flight) with the marignal cell as long as the three cubital 

 cells united. The first cubital cell nearly divided by a distinct (rarely 

 indistinct) but delicate, oblique streak or nervure ; the second cubital 



