20 



THE SCOLYTID BEETLES. 



to the posterior angle is usually greater than the length of the palpifer 

 and stipes, but is sometimes equal and rarely shorter. The ventral 



Fig. 11. — Dendroctonus: Antennae. 1, brevicomis; 3, convexifrons $; 3a, convexifrons (f; 4, frontalis J"; 5, 



arizonicus <S ; 5a, arizonicus ? ; 6, mexicanus; 7, parallelocollis; S, approximatus ? . (Original.) 



1 — a, posterior face of club when antenna is extended at right angles to head, joints 1, 2, 3; 6, anterior face, 



joints 1, 2, 3, 4; d, funiculus, joints 1, 2, 3, 4, 5; c, scape. 



chitinous area of the palpifer and stipes together is always a third 

 or more longer than the combined chitinous parts of the joints of 



Fig, 12, — Dendroctonus: Antennae. 9, monticolx; 10, ponderosse; 12, simplex; IS, pseudotsugx ? ; 14,picea- 

 perda $ ; 15, engelmanni; 17, obesus cf ; 17a, obesus ?. (Original.) 



the palpi. Palpi: The palpi are 3-jointed, the joints connected 

 with each other and with the palpifer by flexible membrane which 

 allows for a certain amount of telescoping, but not adapted for free 



