636 EXTERNAL ANATOMY OF INSECTS. 



angle, more or less acute, with the joint or costal margin, 

 so that the fold is not quite but nearly transverse : this 

 at least is the case in Geotrnpes stercorarius and other 

 Lamellicorns : in Stapkylinus, &c, there are several 

 transverse and longitudinal folds, and thus the wing is 

 more easily packed under the short elytra; in Molorchus, 

 Necydalis, &c, in which it is left uncovered, except at its 

 base, the anal fold takes place, and the apical in some 

 degree; a short portion near the apex forming an obtuse 

 angle with the margin ; in Atractocerus the wing appears 

 to be only longitudinally folded; and in Buprestis vittata 

 only the anal fold is to be detected. Besides these trans- 

 verse and longitudinal folds these organs, in many bee- 

 tles, have an infinity of fine corrugations, which ramify 

 like thenervures of the tegmina of Flata z , &c, proceeding 

 from the Costal Area or the disk of the wing to the pos- 

 terior margin ; the object of these plicatures is doubtless 

 to present a more ample surface to the action of the at- 

 mosphere in flight 6 . When all these folds have been 

 made in a Coleopterous wing, the apex of the one at its 

 posterior margin crosses or rests upon that of the other . 

 In the Dermaptera d , at least the common earwig, 

 there is a triple transverse fold of the wing, and besides 

 this it has numerous longitudinal ones like those of a fan, 

 each of the diverging nervures representing one of the 

 sticks. In the Strepsiptera the folds are only longitudi- 

 nal ; a circumstance which, besides the form and neura- 

 tion of the wing, sufficiently attests that its station is more 

 near the Orthoptera and Coleoptera than the Diptera. 



a See above, p. 611. b See above, p. 613, and Chabrier 



Analyse, &c. 24. c p x , ATY XXI II. Fig. 5. 



" Plate X. Fig. b. 



