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Mr. G. Newport on the 
if stupified and unable to keep on the wing. This was the case 
with several other species, but when deprived of only one antenna 
they seemed, like other insects, to experience but little inconveni- 
ence. 
Now that hearing, as possessed by the larger animals, is purely 
mechanical, there can be little doubt, since the structure of the 
parts, exercised during the enjoyment of the faculty, fully de- 
monstrates their mode of use. These consist in general of the 
ear or external portion, so constructed as to receive within its 
cavity the vibrations of the atmosphere, which, being collected 
within a passage, are considerably augmented, and thrown with 
greater force upon the tympanum, a tense and delicate membrane 
extended across the bottom of the passage, and from this, by 
means of other minute parts, the sensation is conveyed to the 
brain. The importance of this organ — the tympanum — for the 
perfection of the sense, is fully seen, since in no instance with 
which I am acquainted in vertebrated animals possessing the fa- 
culty is this part wanting, although differently situated in different 
species, and also from the loss of the faculty resulting from any 
injury by which the elasticity of the tympanum is destroyed. 
Upon the form of the external ear also the acuteness of the sense 
is considerably dependant. Thus in those vertebrated animals 
which are believed to possess the greatest acuteness of hearing, 
as the hare, rabbit, bat, &c., it is long and tubulated, affording a 
larger cavity for the reception of aerial vibrations, and a longer 
passage before arriving at the tympanum, by which the vibrations 
become very much increased. An approach to this form of organ 
is found in the antennae of a genus of beetles, Coprides , Steph., 
to which, from their habits, we may suppose a greater acuteness 
of hearing to be necessary. These insects, particularly Copris 
molossus, in which I first remarked it, have the antennae com- 
posed of ten joints, the last three of which form the knob or club 
with which it is surmounted. Each of these joints, which are 
long, in the form of leaves, when examined on the under side is 
found to be concave, and constructed like the ears of the hare or 
rabbit, and internally is supplied by the nerves which extend 
through the antennae from the brain. When the insect is in motion, 
these plates or auditory organs, if we may be allowed so to call 
them, are extended as widely as possible, as if to direct the insect 
in its course ; but upon the occurrence of any loud but sudden 
noise are instantly closed, and the antennae retracted as if injured 
by the percussion, while the insect itself stops and assumes the 
appearance of death. A similar use of the antennae is made by 
