1882.] 
Sense of Smell in Insects . 
267 
that the part in question is the seat of the sense of smell. 
On the other hand, not merely constructive but direct evi- 
dence is accumulating to show that this sense in inseCts has 
its seat in the antennae. This evidence I will here endeavour 
as briefly as possible to unfold. 
We will first give a short examination of the antennae in 
the leading inseCt groups, noting particularly in what forms 
they are most highly developed. We find them, firstly, larger 
and more complicated — 
In the males than in the females. 
In adult inseCts than in larvae. 
In nocturnal species than in their nearest diurnal allies. 
In groups possessing a relatively low degree of activity 
than in such as are remarkably swift on the wing. 
In species which depend upon one kind of nutriment 
only as compared with such as are multivorous or 
omnivorous. 
In species which are relatively large than in minute 
forms, which pass their whole career amidst a super- 
abundance of nourishment. 
In forms which lead an independent existence at least 
in the mature state, or in parasites which change 
their host rather than in true Epizoa which infest one 
and the same animal from birth to death. 
In species where the development of the eyes is mode- 
rate rather than in those where it reaches a 
maximum. 
In terrestrial species rather than in the aquatic. 
A few instances will make these differences of development 
more intelligible. 
The sexual distinction is exceedingly striking. In no 
case, as f ar as I am aware, are the antennas of the male 
smaller and simpler than those of the female, whilst in a mul- 
titude of forms there is a well-marked excess in the opposite 
direction. This is very notably the case in the Lamellicorn 
beetles (e.g., Melolontha fullo ), in certain nocturnal Lepi- 
doptera, genera Bombyx, Euthemonia , Arctia, Liparis, Orgyia , 
Odonestris , Saturnia , &c. We meet with the same distinction 
in certain Diptera, where the antennas of the male are 
beautiful plumes * whilst those of the female are simply 
bristles. 
Throughout the entire inseCt-world the antennae of the 
* To the naked eye: much of this grace disappears if they are strongly mag* 
nified. 
