TIIK CKNTS DENDROCTONUS. 



47 



10 9 



7 G 5 4 



3 2 



^ 

 Interspaces 



-T rackets 



Mlia. The media is distinctly connected with a basal, irregular, 

 flexible medial plate, which is joined to the flexor, radial, and sub- 

 scapular plates by membrane and flexible chitin. Near the distal 

 limit of the basal area there is an evident fold or cross vein connecting 

 the base of the media with the base of the cubitus, from which it 

 proceeds outward" to the hinge, and 

 from this point two branches ex- 

 tend to the anal margin. 



Cubitus. The cubitus rises from 

 the outer border of the basal area 

 and apex of the flexor and has two 

 branches. Branch 1 extends to the 

 margin. Branch 2 is short and 

 more or less rudimentary. 



Anal. The anal vein is evidently 

 represented by the broad, short spur 

 arising from the base of the cubitus, 

 and does not extend to the margin. 



Wing attachment. The wing is 

 attached to the body by chitinous 

 dorsal and ventral integument, the 

 latter arising from the dorsal mar- 

 gin of the epimerum, and the for- 

 mer from the lateral margins of the 

 prescutum, scutum, and scutellum, 

 as indicated in the pupa. The heads 

 or roots of the veins are attached 

 by a system of connecting chitinous 

 tendons and ligaments to the pleural 

 and tergal processes and disks. 



Wing articulation. The principal 

 articulation of the wing is between 

 the wing head formed by the costa 

 and subcosta and the condyles of 

 the clavicle and coracoid processes 

 together with the scapular plate. The scapular plate is also con- 

 nected with the prescutal process by articulating membrane and 

 ligaments. 



Pleural clavicula ("clavicula thoracique," Chabrier, 1820). The 

 position and function of the articular processes of the episternum 

 and epimerum (fig. 20, pc), as represented more or less distinctly in all 

 insects, are in Dendroctonus so strikingly analogous with that of the 

 clavicle and coracoid in winged vertebrates as to suggest to the writer 

 the same names. The giving of these names conforms with the prac- 

 tice of adopting for insect anatomy such of the nomenclature of ver- 



FIG. 34. Dendroctonus valens: Diagram of ely- 

 tron, showing striae, interspaces, and tracheae. 

 Striae 1-10; interspaces 1-11. Tracheae: , cos- 

 tal; Sc, subcostal; R, radial; M, medial; Cu, 

 cubital; A, anal. (Original.) 



