351 
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 n , i • £ r\ n 
(from Landois). nervure ot another species ot (Iryllus, 
viz. 6r. 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 Phasgonura 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 transparent as talc, surrounded 
by nervures, and called the speculum. In JEphijppiger 
vitium , a member of this same family, we have a curious 
32 1 Zeitschrift fiir wissenschaft. Zoolog.’ B. xvii. 1867, s. 117. 
33 Westwood, ‘ Modern Class, of Insects,’ vol. i. p. 440. 
