THE GENUS DENDROCTONUS. 127 



bra lighter or red. The sculpture and vestiture of the epistoma, front, 

 pronotum, and elytra vary as usual. The greatest variation is in size 

 ind color. 



Distinctive characters. The characters which distinguish this spe- 

 bies from the next are its smaller average size, slightly less elongate 

 rorm, less shining elytra, with the striae more distinctly impressed on 

 [the sides and the interspaces slightly more convex and more acutely 

 rugose. The difference is not so perceptible in comparing single indi- 

 Ividuals as when many individuals of both species are compared. It 

 I differs from D. borealis by the noticeably more elongate and narrower 

 [pronotum, and from species 17 to 21 it is distinguished by the dis- 

 tinctly impressed lateral striae of the elytra, except D. punctatus Lee., 

 which is at once recognized by the coarse punctures of the declivital 

 striae. It is at once distinguished from D. rufipennis (Kirby) by its 

 smaller size and coarsely punctured and impressed lateral striae. 



Revisional notes. Probably no species of the genus has been in- 

 volved in so much confusion as this. It has been extensively dis- 

 cussed under D. rufipennis, and confused in collections with several 

 other species under this name. There are three specimens in the 

 Le Conte collection labeled "Anticosti," which were evidently the 

 ones referred to in his revision (1876, p. 385). There are also two 

 specimens without locality labels, which may have been the ones from 

 Colorado, while' the one from Alaska is here referred to D. borealis. 

 The smoother and more shining declivity referred to by Le Conte as a 

 distinguishing character relates to the males only. It is represented 

 in the Horn collection by two specimens labeled " Canada," under 

 \D. rufipennis, which were therefore evidently included in Dietz's 

 revision. It is also very probable that the specimens from New 

 Brunswick belonged to this species. 



It is very evident that the barkbeetle referred to under D. rufipen- 

 \nis by Peck, Packard, Hough, and other authors as depredating 

 i on the spruce of New Brunswick, Canada, New England, New York, 

 and Pennsylvania was D. piceaperda. 



Pupa. In addition to the generic, divisional, and subdivisional 



i characters, the apices of the front and middle femora are smooth; 



abdominal tergites 2 to 6 with very small pleural spines; 1 without 



distinct dorsal or lateral spines; 2 to 3 without dorsal, but with two 



i small lateral spines each side; 4 to 6 with a pair of very small dorsal 



and three or four small lateral spines each side; 7 and 8 smooth; 9 with 



usual pleural spines. Pupal type labeled "Hopk. U. S. 377." 



The usual variation in minor details prevails. It is distinguished 

 from the pupa of D. engelmanni by the less impressed vertex of the 

 head and the generally smaller spines and the absence of dorsal 

 spines on the third abdominal tergite. 



Larva. In addition to the generic, divisional, and subdivisional 

 i characters, the front has a slight transverse, rugose elevation situ- 



