396 DR. J. B. HICKS ON THE ORGANS 
melts away ; so that by the time the sac is in the proper focus, the appearance of the otolithe 
has vanished ; and on further examination it will be plainly seen, especially where the 
sac is viewed obliquely, that the appearance of a solid body was an optical deception, pro- 
duced by the looking perpendicularly at the tube which passes from the ‘sac behind the 
tympanum to communicate with the interior of the antenna: as the tube is seldom in the 
centre, the appearance of the **otolithe " is usually more or less on one side. Another 
great proof against the existence of an otolithe is the fact, that when looked at sideways 
the sac is, so far as I can see, perfectly empty. 
M. Lespés, with myself, considers these organs to be none other than auditory; and 
from the numerous researches which have now been instituted by Erichson, Lespés, and 
myself, I think we may safely say that their existence is very general if not universal 
throughout the insect tribes. 
M. Lespés has also pointed out the peculiar hairs which I had noticed some time 
since, and which I have figured in the Plate as they exist on the antenna of Dyticus 
marginalis. 
Note.—The bleaching process which I now adopt is a slight modification of that formerly 
recommended. I take chlorate of potash, say one drachm ; water one drachm and a half; 
mix these in å small bottle with a wide mouth, holding about an ounce; wait five minutes, 
and then add about 12 drachm of strong hydrochlorie acid: chlorine is thus slowly de- 
veloped ; and the mixture remains in action from one to two weeks. 
EXPLANATION OF THE PLATE. 
Ta». LXVII. 
À. Organs on the antenna of Microphora Vespillo. 
Fig. 1. Enlarged view of the organs, 
between the hairs. Diameter 3357 Of an inch. 
Fig. 2. Section of antenna wall, sho 
wing the sacs behind the membrane. 
B. Organs on the antenna of Silpha 
Fig. 1. Enlarged view of organs, 
organs. 
Fig. 2. Section of larger organs. 
À 
as seen from above, on the terminal joint : a a. large sort; 55. smaller 
Diameter at surface 1750 Of an inch. 
C. Organs on the terminal Joint of a Creophilus. 
Fig. 1. Shows the lozenge-shaped groups. 
a a. Organs from 6 to 16 in each group, 
divided by rows of hairs. Diameter 54; of an inch. 
b b. Large organs. 
