\)S W. WE3CHE ON SOME NEW SENSE-ORGANS IN DIPTERA. 



very visible sense-pits, but not exactly similar in structure to 

 those on S. chameleon. Mr. E. E. Austen has described some on 

 Pachygaster meromeloena, Duf.,* and I have found similar sense- 

 pits in Chloromyia formosa, Scop., Pachygaster leachii, Curt., 

 Microshrysa polita, L., and M. Jiavicornis, Mg. 



To sum up the matter, we find in G. equi an insect with 

 a highly developed sense of smell, large antennae, with sense- 

 organs larger than those in S. chameleon and other flies, some 

 of these latter-being known to possess a keen olfactory sense. 

 On the other hand, we have a somewhat similar structure 

 in S. chameleon, of which we have no record that it has 

 a sense of smell, but of which I show that it would be of 

 advantage to possess such a sense ; we now see that the balance 

 is in favour of the affirmative proposition. If we add to this the 

 large amount of evidence recorded by Lord Avebury in Senses 

 of Animals, and Professor Packard in the Textbook of 

 E ' utomology, we get something which is not far from reasonable 

 proof that the antennae carry olfactory organs. The palpi have 

 been regarded as tactile organs, and there is little doubt but that 

 they, in common with the antennae, share this sense. Being 

 •so intimately connected with the mouth, they have been thought 

 to be the seat of the sense of taste. This has been disproved in 

 the case of ants and wasps. These insects, after being deprived 

 of their palpi, still rejected meal mixed with quinine and 

 morphia, though readily feeding on unadulterated meal. I have 

 already shown that in the wasps the taste hairs are on the labium 

 and maxillae, and it is an interesting confirmation of Forel's 

 experiment that I can find none of these organs on the labial or 

 maxillary palpi. As Lord Avebury has continually emphasised 

 in his Senses of Animals, what applies to one genus will not 

 always apply to another, and I have, as already stated, found 

 taste hairs on the labial palpi of A. melifica. 



On the second joints of the palpi of Bibio hortulanus, L., are 

 sense-organs of a very marked type, pits surrounded by ciliated 

 rings of chitin, and on the membrane, stretched across the pits, 

 w r hat appear to be styles or pegs. These I regard as olfactory 

 organs for the following reasons : — 



1. The structure is similar to, or has analogies with, that which 

 we find on G. equi. 



* Entomological Magazine, 1901. p. 24.". 



