150 DR. J. BRAXTON HICKS ON UNDESCRIBED SENSORY ORGANS IN INSECTS. 
which impressions can be conveyed to them, can easily be seen in Diptera, Hymeno- 
ptera, and Lepidoptera. 
The same must be said of those on the legs, which I have described above. If we 
observe an Insect, that joint around which the organs are placed does not touch the 
surface over which it is running, but remains at some distance above it : in this also the 
air must be the medium of communication. 
The delicacy with which odours are perceived by many insects argues an olfactory 
apparatus of considerable perfection ; and it seems to me not improbable that these latter- 
named organs may be in some way connected with the sense of smell, or perhaps with 
some sense not to be found in the Vertebrata. 
In conclusion, I again venture to recommend the process of bleaching by chlorine, to 
which I have already called attention in my former papers. It is easily managed, always 
efficacious, and invaluable in researches of this nature, and equally adapted to decolorize 
Crustacea, Arachnida, and Insecta. Without it, I should have been unable to arrive at 
the results here detailed. 
DESCRIPTION OP THE PLATES. 
Tab. XVIII. 
Halter of (Estrus 
1. Showing the groups of organs (a a) at base on one side; b b, nerves to them. 
2. Section of base : a a a, organs in section ; b b b, nerves proceeding to each group. 
3. Magnified view of the lateral groups : «, seen from above j b, seen in section. 
4. Magnified view of the lower group : a, seen from above ; b, seen in section. 
Fig. B. Under surface of nervure in elytron of Aromia moschata : a a, vesicles ; b 6, nerve proceeding to 
them. 
Hippo b 
H. Hirundinis. Diameter of each vesicle syW inch. 
H 
Musca domestica (a). Diameter of each Wtto i ncn 
Fig. E. Organs on trochanter of Silpha (1 a a). 
2. Enlarged view from above. Diameter of largest xfa inch. 
Fig. F. Organs on trochanter of Lampyris noctiluca (Glow-worm) . 
1. Under surface : a, organs; b, main nerve of leg; c, branches to 
2. Upper surface. 
Fig. G. Trochanter of Meloe. 
l.bb, organs in situ ; a, nerves proceeding to each. 
2. Section of wall, showing the nerve (a) passing to the papilla {b). 
Magnifi 
8 
1. Under surface. 
Forficula 
2. Upper surface. )"' "' ^^ D ™ met " «** *»* 
