20 MISCELLANEOUS FOREST INSECTS. 



area, l)iit the sternellum and poststernellum are not represented by ex- 

 ternal areas. The coxal cavities are not widely separated. The 

 mesothoracic spiracle is large and situated near the ventral edge of 

 the preepisternal process where it is covered by the prothorax. 



The Metathorax. 



The metatergum is quite similar in general character to that in Den- 

 droctonus (Hopkins, 1909, fig. 20); it is shorter and broad, and the 

 postscutellum is very short and declivous. The membranous area of 

 the prescutum is broad. The dorsal band is narrower. The scutellar 

 groove is broad but less produced anteriorly. The metatergal costse: 

 are not elevated above the scutum. The ])rescutal lobes are less 

 prominent and the pleural hooks of the postscutellum are long and 

 slender. Internally the median apodeme is more oblique and more 

 acutely joined to the anterior apodeme. The longitudinal ridges 

 formed by the deep lateral impressions of the scutellar groove are 

 much more prominent and continuous from the anterior apodeme to 

 near the posterior margin. The basal area of the wing and the 

 articulating accessories are similar to those in Dendroctonus, differing 

 only in minor details. 



The metapleura are also similar to those in Dendroctonus, except 

 that the episternum is narrower, the anterior ventral angle more 

 produced and acute, the posterior end narrowed, and the exposed 

 triangular plate of the postepimerum, longer. The chitinous area of 

 the epimerum is narrow, while the submembranous area or post- 

 epimeral area is correspondingly broad. The pleural clavicula is veiy 

 long and the clavicle and coracoid processes are distinctly separated. 



The metasternal area is a third longer than the mesosternal and 

 twice as broad as long, without a median longitudinal groove, but 

 with a median impression toward the posterior margin of the ster- 

 num proper. The sternellum is represented by an intercoxal piece 

 covered by the median process of the abdominal sternite, and flexed 

 beneath this is a plate which evidently represents the poststernellum. 

 The coxal cavities are very large, widely separated, and suppress 

 the first and second abdominal sternites. The metathoracic spiracle 

 is situated in an open space between the metapleural clavicula and 

 the mesepimerum. 



THE ABDOMEN. 



Tergites. — The abdominal tergites increase slightly in length from 

 tergite 1 to tergite 4, inclusive, and also become more uniformly sub- 

 chitinous; 5 and 6 are shorter than 4, and 6 is more membranous 

 and has a pair of membranous lobes which are absent in the five pre- 

 ceding tergites; 7 and 8 are chitinous and clothed with short hairs. 

 The epipleurites are membranous and quite clearly defined in living 

 examples. The spiracle of segment 1 is very large, as usual, and the 



