HENRY J. FRANKLIN. 211 



tennse of some males are somewhat curved from end to end. 

 The term " arcuate " is used to express this curved condition 

 (fig. 17). In some males, the segments of the flagellum are 

 rather strongly convex on one side so as to produce, for that 

 side of the flagellum as a whole, a condition which, in this 

 paper, is described as " crenate " (fig. 23). The males of B. 

 mixtus are peculiar in having a noticeable tuft of hair on the 

 same side of nearly all the segments of the flagellum (fig. 19) ; 

 the tufts on the basal segments being longer and much more 

 noticeable than those on the apical ones. This species ex- 

 cepted, neither the flagellum nor the pedicel bear long hairs ; 

 though such hairs are present on the scape more or less. 

 Minute ferruginous hairs are very numerous over practically 

 the entire flagellum and pedicel. Mixed in with these hairs 

 on one side of all the segments of the flagellum, except the 

 first two, are shallow elliptical depressions or pits in the an- 

 tennal integument. These pits are scattered over about half 

 the surface of these segments. They are also present on a 

 small area on one side of the apical portion of the second 

 segment. Each of these depressions appears to be either 

 lined or covered with a silvery scale or membrane. Figure 

 56 shows the outlines of several of these pits with the smaller 

 hair punctures mixed in with them. These depressions may 

 be sense organs. They are present in all species and castes. 



Organs of Vision. 

 Eyes. — The compound eyes are usually and narrow with 

 rounded ends, and are placed antero-laterally on the head. 

 They follow to some extent the curvature of the sides of the 

 head and are, therefore, themselves convex aud usually some- 

 what arcuate from end to end. In some males {Bombias 

 spp.), they are greatly widened, lengthened and swollen and 

 very convex, bulging out from the sides and the top of the 

 head. The proportional length of the eyes varies very con- 

 siderably between Psithyrus, the subgenus Bonibus and the 

 subgenus Bombias and also between various species of the 

 latter subgenus. It is least in Psithyrus and greatest in 

 Bombias. The elongation of the longer eyes is effected by 



TRANS. AM. ENT. SOC. , XXXVIII. 



