354 SEXUAL SELECTION. Part II. 



scribed by Landois, 32 of from 131 to 138 sharp, trans- 

 verse ridges or teeth (st) on the under side of one of the 

 nervures of the wing-cover. This toothed nervure is 

 rapidly scraped across a projecting, smooth, hard nervure 

 (r) on the upper surface of the opposite wing. First 



one wing is rubbed over the other, 

 and then the movement is reversed. 

 Both wings are raised a little at the 

 same time, so as to increase the re- 

 sonance. In some species the wing- 

 covers of the males are furnished at 

 the base with a talc-like plate. 33 I 

 have here given a drawing (fig. 11) 

 Fig. ii. Teeth of Nervure of the teeth on the under side of the 



of Gryllus domesticus ? ,i • j? ri 11 



(from Landois). nervure oi another species 01 Uryllus, 



viz. G. domesticus. 



In the Locustidse the opposite wing-covers differ in 

 structure (fig. 12), and cannot, as in the last family, 

 be indifferently used in a reversed manner. The left 

 wing, which acts as the bow of the fiddle, lies over the 

 right wing which serves as the fiddle itself. One of 

 the nervures (a) on the under surface of the former is 

 finely serrated, and is scraped across the prominent 

 nervures on the upper surface of the opposite or right 

 wing. In our British Pliasgonura viridissima it ap- 

 peared to me that the serrated nervure is rubbed 

 against the rounded hind corner of the opposite wing, 

 the edge of which is thickened, coloured brown, and 

 very sharp. In the right wing, but not in the left, 

 there is a little plate, as transrjarent as talc, surrounded 

 by nervures, and called the speculum. In Ephippig&r 

 vitium, a member of this same family, we have a curious 



3: - ' Zeitsehrift fur wissenschaft. Zoolog.' B. xvii. 18G7, s. 117. 

 :i3 Westwood, ' Modern Class, of Insects,' vol. i. p. 440. 



