ii Proceedings of the South African Pliilosophical Society. 



Better developed in the male, and sometimes restricted to him, 

 these musical organs are often present in the female, although 

 seldom as highly developed as in the male. Contrary, however, to 

 the usual belief, many a female is apt to produce shrill, piercing 

 notes which sometimes, but seldom, so far as is now known, equal 

 that of the male in power and volume of sound. 



But just as the protective resemblance is of two sorts, the 

 phonation of insects is also of two kinds, viz. : — 

 I. For challenge or wooing purposes. 



II. For defensive purpose. 



Phonation for loooing purjoose. 



It is in the Orthopterous order of insects that the stridulating, 

 or music-producing organ, as well as the auditory organs, are most 

 developed. 



We shall take them in systematic order. 



Mantince. — Among our South African species I have not been able 

 to ascertain the stridulation reported to have been observed among 

 the MantincB, but Empusa, when seized, does occasionally produce 

 a noise by rubbing its wings together. The membranaceous cover- 

 ings rubbed against the asperities of the dorsal part of the abdomen 

 produce this sound which, however, in this raptorial species could 

 be used only as a means to frighten an enemy. 



Gryllincd-Loctcstince. — The Gryllince and Loctistincd are especially 

 adapted to produce music of a high class ; that is if the volume and 

 the continuation qf the sound be the only consideration. 



Most of you are acquainted with that of the House Cricket, 

 perhaps the best virtuoso among its kindred. If we want to 

 ascertain how the musical sound is produced, we find that in the 

 male the basal part of the upper wing bears on one side a file on the 

 inner surface, and the other wing has a sharp, marginal edge ; by 

 raising the upper wings and rubbing them rapidly, the animal, 

 through the friction of one wing against the file, or serrulate part of 

 the other, produces a rasping noise. The insect is able in some 

 cases to modify or to increase the sharpness of this noise by raising 

 the anterior part of the body {pronotum), or by altering the angle of 

 the upper wings, which are raised when vibrating. 



To describe these stridulating organs would prove too technical 

 a task. In the two Sub-Families, Gryllince and LoctcstincB, they are 

 based on the same plan. But the noise produced is not always in 

 the proportion of the length of the wings, or body, or of the anal 

 surface which is to act as a resounding board. In the case of 



