MORPHOLOGY OF THE LEGS OF HYMENOPTEROUS INSECTS.- 443 



Let us first consider the anterior or pro-thorocic legs of the honey-bee. We 



first notice (Fig. 1) a strong and interesting modification in the basal tarsus 

 a,nd tibial spur, which modification is known as the "antenna cleaner." At 

 the base of the first tarsal joint and in the angle between it and the tibia 

 is a short, hollow semi-cylinder. The concave surface of this cavity is smooth 

 except at the outside margin, where there are from seventy-eight to ninety 

 projecting hairs, which under the microscope remind one of the villi of the 

 small intestines of mammals. These teeth, like hairs, projecting as a fringe, 

 form a most delicate brush. The tibial spur is so modified as to resemble a 

 very short handled razor, the blade of which is for a wide space facing the 

 tarsus, a most delicate membrane, and this blade forms a sort of lid to the 

 cavity just described. When the leg is straight this lid barely reaches the 

 cavity; but when the first tarsus is flexed upon the tibia it serves as a cover 

 to the cavity and really closes it. 



This peculiar structure is found in both sexes and in the abortive females 

 or workers of social bees, in all other bees, in all wasps so far as I 

 have examined, in the Mutillida3, in ants, in all the families of parasitic 

 hymenoptera except the Chalcids, while in the Oynips, Cynipid^, Saw 

 flies, Tenthredinidse, and horn-tails, Uroceredae, we find it nearly or quite 

 absent. 



We find the " antenna cleaner " in all species of bees — Apidse — even in 

 the curious species like the male of Megachile (Fig. 2.), where the whole 



anterior leg is remarkably modified. 

 In the bumble-bees species of the 

 genus Bombus we find the antenna 

 cleaner almost exactly like that of 

 the honey-bee, except the part which 

 V '^ / " i ■ -'fif^'' " ' "''li^^'' I have termed the blade, in the modi- 



Fig. 5. fied tibial spur has its back more 



