108 ENTOMOLOGY 
faces of the membrane is equalized by means of an adjacent 
spiracle, which admits air to the inner surface. Resting 
against the inner face of the tympanum are two processes 
(Fig. 137, p, Pp), which serve probably to transfer the vibra- 
tions, and there is also a delicate vesicle connected by means 
of an intervening ganglion 
Fic. 138. 
with the auditory nerve, which 
in this case comes from the 
metathoracic ganglion. The 
nerve terminations consist of 
delicate bristle-like processes 
which are probably affected by 
the oscillations of the fluid con- 
tained in the vesicle just re- 
terredsto. 
Other tympanal organs, 
doubtless auditory, are found 
on the fore tibize of Locustidee, 
ants, termites and Perlidz, on 
the femora of Pediculidze and 
the tarsi of some Coleoptera. 
IRL ‘ ' 
Hy Several types of chordotonal 
‘al Kee, ‘I pene : 
organs have been described, of 
which those of the transparent 
Chordotonal sense organ of aquatic Corethra larva may serve as an 
dipterous larva, Corethra plwmicornis. 5 
cd, cord; cg, chordotonal ganglion; f, 
fibers of an integumental nerve; g, ated on each side of abdominal 
ganglion of ventral chain; /, ligament; 
m, longitudinal muscles; , chordotonal segments Ake MICO}, inclusive, cons 
nerve; rv, rods (nerve terminations); ¢, ease im OTN c 
5h sis tig. 138 s 
tactile sete.—After GRABER. ist each (Fig 138) of a tense 
example. These organs, situ- 
cord, probably capable of vibra- 
tion, which is attached at its posterior end to the integument 
and at its anterior end to a ligament. Between the cord and 
the supporting ligament is a small ganglion, which receives ea 
nerve from the principal ganglion of the segment. 
Vision.—The external characters of the two kinds of eyes 
have already been described. 
—ocelli and compound eyes 
