ANATOMY AND PHYSIOLOGY. s- 1.432 
is supplied with an apparatus by which its edge can 
be drawn tight and laid in apposition with the strong 
edge of the larger segment, so as to close the pas- 
sage between them. This is the respiratory larynx, 
nearly answering to our epiglottis, or to the upper 
larynx of birds. Its function is simply to admit or 
exclude the air. The proper instrument of voice, 
answering to our vocal cords or nearly so, is a little 
horny comb, which is placed across this cleft, and 
vibrates, like the tongue of a Jew’s harp or accordion, 
with the passing current of air. 
Turning now to the thoracic spiracles of the proper 
subject of this inquiry:—I regret much that Dr. 
Landois has not made the spiracles of wasps the sub- 
ject of his special study, but has left us only the 
analogy of the corresponding. parts of allied insects 
for our guidance. Really the difference between the 
vocal organs of the hornet and of the humble-bee is 
very considerable. After rubbing off the hairs from 
the outside of the thorax, we shall find the orifices of 
the spiracles, as already traced im the anatomy of the 
thorax, without much difficulty. They are linear, 
not mere pin-holes as in the abdomen, and slightly 
crescentic in form, with the convexity directed back- 
wards. The meta-thoracic spiracle is somewhat the 
smaller of the two, but, beng situated in one of the 
scales, and not, like the pro-thoracic, between two of 
them, it is more easily removed without any displace- 
ment of its parts. The integuments containing it 
should be sliced off with a sharp scalpel, making the 
specimen as thin as possible, so as to allow of the 
near approach of the object glass. And it will need 
all the aid of turpentme to make the dark horny 
