10 THE SCOLYTID BEETLES. 
In species 12 to 21 (subdivision C) the sexes are easily distinguished 
by the differences in the declivity of the elytra. In the females the 
stride are more distinctly impressed and the interspaces more convex 
and roughened. In the males the stride are much less or not at all 
impressed and the interspaces are shining, smooth, and often 
punctured. 
In species 12 and 13 (section a 3 ) the striae are deeply impressed 
in both sexes; but in species 14 to 21 (section a 4 ) they are rarely 
impressed in the males. * 
In species 22 and 23 (subdivision D) the sexes are less distinctly 
defined by external characters. In the. females the antennal club is 
broader, stouter, and more compressed; the head is narrower and the 
mandibles are smaller, while the reverse is true in the males. 
THE EGG. 
The eggs of the majority of the species have been observed and 
apparently show no differences except in relative size, corresponding 
with the size of the adults. They are slightly oblong, rounded at the 
ends, pearly white, and shining. 
THE LARVA. 
The larva (fig. 4) is a stout, cylindrical, yellowish- white, footless 
grub with a yellowish shining head. The body is deeply and closely 
wrinkled, as shown in the figure. 
In species 1 to 11 the dorsal surface of the 8th and 9th abdominal 
segments are smooth, without chitinous plates, and the ventral pro- 
thoracic lobes are more or less prominent. 
In species 1 and 2 the front is without a median elevation. 
In species 3 to 7 the front has a more or less rounded convex 
elevation. 
In species 9 to 11 the front has a transverse roughened elevation, 
slightly more elevated toward the sides. 
In species 12 and 13 the dorsal surface of the 8th and 9th abdominal 
segments is without chitinous plates. 
In species 14 to 23 one or both have distinct plates. 
In species 14, 15, 17, and 19 the 8th and 9th abdominal plates are 
without prominent spines. The, frontal elevation, when present, is 
transverse. 
The larva? of species 16 to 18 and 19 have not been observed. 
Species 21 has a roughened plate on the 9th segment, but none on 
the 8th. 
In species 12 the front is without a median elevation, but in spe- 
cies 13 there is a distinct transverse, rugose, median elevation, more 
elevated toward the sides. 
