228 ORGANS OF SENSE 
sometimes the presence of air renders them very con- 
spicuous, they are in others by no means easy to make 
Fig. 7. 
mn 
Ww 
Diagrammatic section through part of Fig. 6. 
e, chitinous skin of the antenna. e¢, two of the cork-shaped 
organs. s, external chamber of one of the stethoscope-shaped 
organs. %, the tube. w, the posterior sac. mn, the nerve. 
out ; and I think that when a small number only are 
apparently present, this is probably due merely to the 
fact that the others are not brought out by the mode 
of preparation. 
In addition to the group of these organs situated 
in the terminal segment, there is one, or in some rare 
cases I have found two, in each of the small preceding 
segments. The tubes in these segments appeared to 
the eye to be nearly of the same length as those in the 
terminal segment, but I could not measure their exact 
length, as they do not lie flat. In some cases, when 
the segment was short, the tube was bent—an indica- 
tion, perhaps, that the exact length is of importance. 
Tt is possible that these curious organs may be audi- 
tory, and serve like microscopic stethoscopes. Professor 
Tyndall, who was good enough to examine them with 
me, concurred in the opinion that this was very pro- 
bable. I believe I am correct in saying that the bend- 
