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. ll.Dendroctonus: Antennae. 1, brevicomis; 3, convexifrons 9; 3a, convexifrons tf; 4,frontalis J 1 ; 5, 



arizonicus cf; 5a,arizonicus 9; 6 , mexicanus; 7 , parallelocollis; 8,approximatus 9. (Original.) 



Ia, posteriorface 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: Antennse. 9, monticolse; 10, ponderosse; 12, simplex; 13, pseudotsugx 9 ; 

 perda 9 ; 15, engelmanni; 17, obesus tf; 17a, obesus 9. (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 



