12 THE SCOLYTID BEETLES. 



with or without dorsal, lateral, and pleural spines, which vary in size 

 among the different species from very smooth to quite coarse and 

 prominent. 



In species 1 to 5 and 8 to 11 the vertex or front of the head is 

 grooved, with prominent or small fleshy spines situated at each side 

 of the groove. 



The pupae of species 6 and 7 have not been observed. 



In species 1 to 5 and species 8 the elytral pads are smooth and the 

 abdominal segments have small lateral spines or tubercles. 



In species 1 and 2 the vertex of the head is faintly grooved, the 

 spines are small and widely separated, and the front and middle 

 femora are without apical spines or granules. 



In species 3 the vertex is faintly grooved, the spines are very small, 

 and the front and middle femora have apical granules. 



In species 4, 5, and 8 the vertex is broadly grooved, the spines are 

 moderately small and widely separated, and the front and middle 

 femora have small apical tubercles. 



In species 9, 10, and 11 the elytral pads are roughened, with 

 sparsely placed granules. The head has the vertex deeply grooved 

 and the spines prominent, and the abdominal segments have very 

 long lateral spines. In species 9 and 11 the front and middle femora 

 have two apical spines each, while in species 10 they have one each. 



In species 12 to 23 the vertex is either faintly impressed or convex, 

 with an acute granule at each side and one or two on each side on the 

 front. The elytral pads are smooth, and the abdomen has more or 

 less prominent lateral spines. 



In species 12 and 13 the vertex of the head is faintly impressed or 

 grooved, and the front and middle femora are without granules or 

 spines. 



In species 14 to 23, so far as observed, the vertex is convex, and 

 the femora have small apical granules. 



EGG GALLERIES, LARVAL MINES, AND PUPAL CELLS. 



(See figures of work.) 



In species 1 to 11 the egg galleries are winding to straight, with 

 individual larval mines concealed or exposed in inner bark and with 

 the pupal cells either in the outer or in the inner bark. 



In species 1 to 8 the egg galleries are winding, nearly transverse to 

 oblique; the larval mines short, not in groups; and the pupal cells 

 are in the outer bark. In species 1, 2, 5, 6, 7, and 8 the larval mines 

 are concealed, while in species 3 and 4 they are exposed in the inner 

 bark. 



In species 9 to 11 the egg galleries are longitudinal, slightly wind- 

 ing to straight. The larval mines are short and usually in groups, 



