Morphology of the Legs of Hymenopterous Insects. 197 
flies—Cynipide. In the saw-flies—Tenthredinide—(Fig. 7), there 
is no hint of the cavity on the first 
tarsus; but a slight concavity of the 
spur, with the membrane just visible, 
still suggests the “ pollen cleaner.” In 
the horn-tails—Uroceridze—the only re- 
minder we have of the antenna cleaner is in the slightly curved spur. 
The membranous part of the blade is wholly wanting. 
In the study of this apparatus I have been very much interested 
to note how persistent is its type within each family. I have care- 
fully examined very numerous specimens, and I think we could, 
from the study of this organ alone, arrange the species of Hymen- 
optera, with very few exceptions, in their respective families. The 
same is also true in many cases of genera. We shall not wonder 
at this as we come to study the function of the organ and note its 
great importance. 
No one who has studied bees closely can doubt for a moment the 
functional importance of the antenne. As touch organs, they are 
most delicate and wonderful. The work of the hive bee is largely 
performed in total darkness. Yet very intricate operations are 
carried on with unerring exactness. This is only possible through 
the aid of those very sensitive tactile organs—the antenne. There 
is hardly less doubt that the antennz are the scent organs of insects. 
And with Hymenopterous insects, especially of the higher families, 
the sense of smell is of exceeding importance. It has been thought 
also that the antennæ serve as organsof hearing. This, however, is 
Probably not true. We see then that it is of the highest 
importance that these organs be kept free from all dust. 
But the very habits of most Hymenopterous insects, visiting, 
as they do, flowers laden with pollen, as do all except the lowest 
families, or digging in the mud and dust, as do many bees and 
Wasps, tend to soil the antenne. And it is no more necessary for 
the microscopist to brush the lenses of his objectives than for the 
bee or wasp to dust its antenne. 
That the function of the apparatus just described is to brush or 
free from dust the antenna is easily proved by experiment. We 
have only to imprison a bee or wasp on the window pane of our 
room, and quietly dust its antennæ with lime or flour, when we will 
See it pass an anterior leg forward, draw an antennæ through the 
Fig. 7. 
