442 MODERN CLASSIFICATION OF INSECTS. 



appear much larger than when it is at rest, the lateral part of each 

 being suddenly deflexed, so as to cover the sides of the body ; but as 

 the sides are curved, a narrow membranous piece is inserted at the tip, 

 between the dorsal and lateral pieces, extending to some distance 

 along the wing- covers, and which is concealed when the wings are 

 closed; the veins which traverse the talc-like part of the wing-covers 

 of the males are thick and very irregular in their disposition, and 

 vary in their position in different species. In the males of the 

 house and field-crickets, on the internal margin (^Jig. 54. 7. repre- 

 sents one of the wing-covers of the male, 54. 9. ditto of the female, 

 and 54. 8. one of the wings of the former species), about one-third 

 of its length from the base, a thickened point is observed, from 

 whence several strong veins diverge, forming an angle from this 

 point. The strongest of these veins, which runs towards the base of 

 the left wing-cover is found on the underside to be regularly notched 

 transversely, like a file ; when the wing-covers are closed, this oblique 

 bar of the wing-cover lies upon the upper surface of the corresponding 

 part of the right wing-cover ; and when a tremulous motion is im- 

 parted to the wing-covers, this bar rubs against the corresponding bar 

 of the right wing-cover, and thus produces a vibration, which is com- 

 municated to the other parts of the wing-covers ; which, being divided 

 into a number of irregular spaces, have each a distinct vibration, and 

 pi'oduce a sepai-ate sound, which unitedly forms the stridulation or chir- 

 rup so well known. I must refer to M. Goureau's elaborate paper upon 

 this subject in the Annales Soc.Ent. de France, 1837, p. 31. (and trans- 

 lated in the Entomological Magazine for that year), and to a memoir 

 by Latreille in the eighth volume of the Mernoires du Museum, for 

 numerous particulars and details concerning the mode in which the 

 sound is produced in the species above-mentioned, as well as in several 

 other crickets, including the mole-cricket, which, according to Latreille, 

 stridulates only in the evening and night. M. Goureau was able to 

 produce the sound artificially, by rubbing the elytra of the males of 

 this species against each other, although their organs of stridulation 

 are far less strongly marked than in the others; indeed, as the 

 females are destitute of an exserted ovipositor, it is only hy a minute 

 inspection of the veins of the wing-covers that the sexes may be 

 distinguished. The females in this family are not able to make a 

 noise, the veins of" their wing-covers being more regularly disposed 

 (Jig. 54. 9.). 



