146 TRUE TALES OF THE INSECTS. 



integfument. That these orofans on the leg's of Locustidse 

 are auditory organs has been ascertained beyond doubt. 

 It is, in fact, only reasonable that insects provided with 

 special sound-producing apparatus, as we shall presently 

 see the Locustidae are, should also be furnished with 

 specialized ears, 



A structure of a remarkable nature occurs in con- 

 nection with the ears. At the posterior lateral angle of 

 the prothorax, just over the insertion of the front leg, 

 an open orifice is found ; it is quite close to the protho- 

 racic stigma, but is larger than it ; it communicates with 

 the one on the opposite side, and from them there 

 extend processes along the anterior legs that narrow in 

 passing the knee, and at last dilate in the tibiae, so as 

 to form longitudinal vesicles, one of which is in proximity 

 to each tympanum of the ear. This prothoracic orifice, 

 which exists in the two sexes, among nymphs, and 

 among larvae, and these leg-tracheae, do not communi- 

 cate with the tracheal system. Why the acoustic organs 

 should require a supply of air other than that which 

 could be obtained through the ordinary tracheal system, 

 remains to be determined. 



Although these tibial organs of Locustidae have 

 certainly the function of hearing, there is great difficulty 

 in deciding as to the exact kind of sounds to which they 

 are sensitive. Nor is it even understood how the sounds 

 are transmitted to the nerves. 



