Auditory Aj)parattifi of the Culex mosquito, 353 



has Ijcen discovered in these later times a single organ having 

 the conditions essential to an auditory apparatus. This organ 

 consists, in the Acridid;e, of two f'osssc 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. Tiiis 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 inmiediate 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 Latrcille. J. Muller was 

 the first who fortunately conceived that in Gryllus hieroyly- 

 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, CEdipoda, 

 Podisiiia, Calopteiius, and Truxalis.) 



"The Locustid;e and Achetidze have a similar organ situated 

 in the fore legs directly below the femoro-tibial articulation. 

 With a part of the Locustidfe {Mecoaema, Borbitistes, Phanero- 

 ptera, PhijUopteru), there is on each side of this point a fossa, 

 whde with another portion of this family there are at this 

 same place two more or less spacious cavities (auditory cap- 

 sules) provided with orifices opening forward. These fossje 

 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 

 anterior side of the trachean vesicle. Upon this band is situ- 

 ated a row of transparent vesicles containing the same kind of 

 cuneiform staflF-like bodies, mentioned as occurring in the 

 Acrididae. 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 Acrididte, a part of this 

 trachean apparatus may be compared to a tuba Eustachii. 

 In the Achetida there is on the external side of the tibia of 

 the fore legs an orifice closed by a white silvery membrane (tym- 

 panum), behind which is an auditory organ like that just de- 

 scribed. (With Ac/ieta achatina and italica there is a tympanum 



