Auditory Apparatus of the Culex mosquito. 30d 
has been discovered in these later times a single organ having 
the conditions essential to an auditory apparatus. This organ 
consists, in the Acridide, of two fossze or conchs, surrounded 
by a projecting horny ring, and at the base of which is attached 
a membrane resembling a tympanum. On the internal surface 
of this membrane are two horny processes, to which is attached 
an extremely delicate vesicle filled with a transparent fluid and 
representing a membranous labyrinth. This vesicle is in con- 
nexion with an auditory nerve which arises from the third tho- 
racic ganglion, forms a ganglion on the tympanum, and termi- 
nates in the immediate neighbourhood of the labyrinth by a 
collection of cuneiform staff- like bodies with very finely pointed 
extremities (primitive nerve-fibres ?), which are surrounded by 
loosely aggregated ganglionic globules. (This organ has been 
taken for a soniferous apparatus by Latreille. J. Miiller was 
the first who fortunately conceived that in Gryllus hierogly- 
phus this was an auditory organ. He gave, however, the inter- 
pretation only as hypothetical; but I have placed it beyond all 
doubt by careful researches made on Gomphoceros, Uidipoda, 
Podisma, Caloptenus, and Truaalis.) 
“The Locustidze and Achetide have a similar organ situated 
in the fore legs directly below the femoro-tibial articulation. 
With a part of the Locustidee (Meconema, Barbitistes, Phanero- 
ptera, Phylloptera), there is on each side of this point a fossa, 
while with another portion of this family there are at this 
same place two more or less spacious cavities (auditory cap- 
swes) provided with orifices opening forward. These fossze 
and these cavities have each on their internal surface a long- 
oval tympanum. ‘The principal trachean trunk of the leg 
passes between two tympanums, and dilates at this point into 
a vesicle whose upper extremity is in connexion with a gan- 
glion of the auditory nerve. This last arises from the first 
thoracic ganglion, and accompanies the principal nerve of the 
leg. From the ganglion in question passes off a band of ner- 
vous substance which stretches along the slightly excavated 
auterior side of the trachean vesicle. Upon this band is situ- 
ated a row of transparent vesicles containing the same kind of 
uneiform staff-like bodies, mentioned as occurring in the 
Acridide. ‘The two large trachean trunks of the fore legs open 
by two wide infundibuliform orifices on the posterior border of 
the prothorax; so that here, as in the Acridide, a part of this 
trachean apparatus may be compared to a tuba Eustachii. 
In the Achetidee there is on the external side of the tibia of 
the fore legs an orifice closed by a white silvery niembrane (tym- 
panum), behind which is an auditory organ lke that just de- 
scribed. (With Acheta achatina and italica there is a tympanum 
