194 Morphology of the Legs of Hymenopterous Insects. 
most modified and very important in systematic mammalogy. For 
like reason the ornithologist looks to bill and feet in his study of 
families and genera, With the laws of variation and adaptation 
before us, we should expect to find modification carried to extremes 
‘among Hymenopterous insects. The life functions of these insects 
are so wonderful and varied that a maximum differéntation of or- 
gans and structure is required for their execution. The chief tools 
used by these Hymenopterons are the legs and mouth organs, and 
it is to the former that I invite attention. 
Let us consider the anterior or prothoracic legs of the honey-bee. 
We first notice (Fig. 1) a strong and interesting modification in 
the basal tarsus and 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. 
The 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 Mutillide, Formicide in ants, in all 
the families of parasitic Hymenoptera except the Chalcids, while in 
the Cynips, Cynipide, Saw flies, Tenthredinide, and horn-tails, 
Uroceridee, we find it nearly or quite absent. 
We find the “antenna cleaner” in all species of bees—Apide— 
even in the curious species like the male of Megachile (Fig. 2), 
where the whole ante- 
rior leg is remarkably 
modified. Inthe bumble- 
bees species of the genus 
Bombus we find the an- 
tenna cleaner almost 
