3o6 



ORTHOPTERA 



CHAP. 



are said by Brunner and de Saussure to be so great as to affect 

 even the generic characters, and give rise to the idea of an 

 " uncompleted species-formation." 



Methone anderssoni, an inhabitant of the Karoo Desert of South 

 Africa, is one of the largest of the Acridiidae. A female of this 

 species is represented of the natural size in Fig. 185. This 

 Insect is remarkable on account of the complex organs for pro- 

 ducing sound, and for the great modification of the posterior legs 

 (Fig. 185, &), which do not possess locomotive functions, but serve 



as a portion of the sound- 

 producing apparatus, and as 

 organs for protecting the sides 

 of the body. This Insect is 

 said to be very efficient in 

 making a noise. The sexes 

 differ considerably in their 

 sound - producing organs, a 

 portion of which are present 

 in the female as well as in 

 the male (Fig. 186). Con- 

 nected with the first abdominal 

 segment, but extending back- 

 X2^ c 1, ^J e wards on the second, there is 



Fig. 186. Portions of middle of the body and ^ peculiar swelling bearino- 



liiudleg of Methone anderssoni (i: a, femm; ^ i i 



b, an inferior fold; c, rattling - plate ; d, two or three Strongly raised 



striated surface ; e, the adjoining sculpture ; ^hitinous folds CFm. 186, c). 

 /, grooved portion of tegmen. Ine part e . , 



is really, like d, a portion of the second When the leg is rotated these 



SgrlTL4p='rorthtfi*gte.*'''^'' " folds are struck by some peg- 



like projections situate on the 

 inner face of the base of the femur, and a considerable noise is 

 thus produced. The pegs cannot be seen in our figure. This 

 apparatus is equally well developed in female and male. On the 

 second abdominal segment, immediately behind the creaking folds 

 we have described, there is a prominent area, densely and finely 

 striated (Fig. 186, d): this is rubbed by some fine asperities on 

 the inner part of the femur near its base. Sound is produced by 

 this friction on the striated surface, the sculpture of which is 

 abruptly contrasted with that of the contiguous parts : these struc- 

 tures seem to be somewhat better developed in the male than they 

 are in the female, and to be phonetic, at any rate in the former sex. 



