332 ORTHOPTERA 



simple, somewhat fan-like arrangement ; the little transverse 

 nervules exhibit only slight variety. These wings are frequently 

 rolled up at the apex, and project beyond the body like an 

 additional pair of cerci (Fig. 204). The abdomen is chiefly 

 remarkable for the large development of the pleura, the stigmata 

 being consequently very conspicuous. The cerci are not jointed, 

 though they are flexible and, often, very long ; they bear a 

 variety of sense-organs (Fig. 67). The saltatorial powers of the 

 crickets are frequently considerable. 



Graber has observed the post-embryonic development of the 

 field-cricket, Gryllus campestris, though unfortunately not from 

 the very commencement, so that we do not know whether there 

 are five, six, or seven ecdyses ; the number is probably either six 

 or seven. The manner in which the alar organs are developed is 

 similar to that we have described and figured in the Locustidae. 

 In the earlier instars there is a slight prolongation of each side 

 of the meso- and meta-notum, but about the middle of the 

 development a considerable change occurs the rudimentary 

 organs then become free appendages and assume a different 

 position. 



The Gryllidae possess a pair of tympana on each front leg, 

 but these organs contrast with those of the Locustidae in that 

 the pair on each leg usually differ from one another, the one on 

 the outer or posterior aspect being larger than that on the inner 

 or front face of the leg. 



The ears of the Gryllidae have not been so well investigated 

 as those of the Locustidae, but are apparently of a much less 

 perfect nature. No orifice for the admission of air other than 

 that of the prothoracic stigma has been detected, except in 

 Gryllotalpa. On the other hand, it is said * that in addition to 

 the tibial organs another pair of tympana exists, and is seated 

 on the second abdominal segment in a position analogous to that 

 occupied by the ear on the first segment of Acridiidae. 



The musical powers of the crickets are remarkable, and are 

 familiar to all in Europe, as the performance of the house-cricket 

 gives a fair idea of them. Some of the Insects of the family are 

 able to make a very piercing noise, the note of Bracliytrypes 

 nicrjaceplialus having been heard, it is said, at a distance of a 

 mile from where it was being produced. The mode of produc- 

 1 Brunner, Verh. zool.-bot. Gcs. Wien, xxiv. 1874, p. 288. 



