46 



THE SCOLYTID BEETLES. 



hinge. It arises through the radial plate from the subscapula, and 

 joins and fuses with the head and posterior edge of the subcosta to 



Fig. 22.—Dendrocfonus valens: Basal process of right elytron. A, Ventral; B, latero-sinistral; C, dorsal; 

 D, latero-dextral; a, foramen of articulatory head; 6, subcostal head; c, costal head; d, costal fold; e, 

 costal margin; /, callus; g, basal foramen; h, anal fold; i, muscle disk; j, radial plate; k, posterior ven- 

 tral area; I, anal margin; m, posterior dorsal area; Sc, subcostal area. (Original.) 



Fig. 33. — Dendroctonus valens: Declivital section of elytra, a, Ventral shoulder; 6, dorsal shoulder; c, 

 sutural tongue; d, ventral lip; e, dorsal lip;/, sutural groove; </, rugose surface of apical wing-lock; h, 

 stridulating rasp; i, apical wing-lock; j, suture; A, anal canal; Cu. cubital canal; M, medial canal; R 

 radial canal; Sc, subcostal canal; C, costal canal; D, transverse section; E, ventral aspect; F, trans- 

 verse section through stridulating rasp; G, right elytron; H, left elytron. (Original.) 



the point where it becomes broadened and obliquely rugose. Here 

 it separates from the subcosta and joins the media by a short cross- 

 vein, and thence proceeds, as shown in the figure. 



