314 OETHOPTEEA. 



enclosing small hyaline cells. The remaining parts of the dorsal field, i. e. the apex, 

 inner and outer margins, are more or less coriaceous and green in colour *. 



The conclusion to be drawn from this analysis is that the left elytron is the fiddle- 

 bow of the musical instrument, and that the right elytron is the tambourine which 

 produces the sounds. 



The musical instrument is here very simple as compared with that of the Gryllidse, 

 and, on account of its rougher surface, must certainly produce less varied and less 

 musical sounds. 



Hind wings. — These present at the base of the posterior field two strong transverse 

 veins fusing together in an acute angle. The anterior vein is somewhat • oblique ; 

 the posterior one is transverse and formed by the heads of the radiate nervures of 

 the hind field anastomosed together into a chitinous arch, which forms a support 

 for them. 



This sort of vein, in the shape of a V, might be termed, following Brunner v. 

 Wattenwyl, the vena plicata ; but it is not homologous with his vena plicata of the 

 tympanum of the male elytra (comp. antea, p. 312, notef), for it has not the same 

 position, and, besides, its angle is turned in a contrary direction (the angle outside, 

 instead of inside), and, in addition, it is found in both sexes. Moreover, such a vena 

 flicata exists also at the extreme base of the elytra, near their articulation ; but it is 

 very small and not always evident, its separate parts being frequently disunited. 



The Phaneropterinse live mostly in bushes and on trees. They are all mimetic 

 insects, their oblong, ovate, or lanceolate elytra, placed in a perpendicular plane, 

 exactly imitating leaves. Most of them are green in colour ; others are variable in 

 this respect, green or brownish, imitating living and dead leaves, perhaps according to 

 the season. They fly very readily. In all the known Central- American genera (except 

 Dichopetala, $ ) the elytra and wings are completely developed. 



* The appearance of the musical field as we have described it is rarely evident, the whole of the veins being 

 seldom developed in a normal manner. They are frequently fused together by becoming thickened or inter- 

 rupted for the purpose of forming the tympana. — In the left elytron, the second axillary vein, instead of joining 

 the inner end of the stridulating vein, is often interrupted at its angle, so that the second transverse vein 

 seems to be independent. In both elytra, too, the normal venulation is often considerably modified by the 

 extension of the coriaceous reticulation of the dorsal field. In the right elytron the tambourine when invaded 

 by such reticulation is no longer apparent and is reduced to a less musical instrument. "What we have 

 endeavoured to do is to describe the theoretic typical structure of the musical field, based on its homologies 

 independently of the various appearances which it may present. 



