718 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 
main galleries cross each otber, while in another case two unite to 
make a figure 8, but in such a case the secondary galleries do not 
cross the main 01)68, and in examples where two main galleries run 
parallel and somewhat near each other, they do not send secondary 
galleries into the narrow interspaces between the two main galleries. 
On submitting specimens of the beetle to Dr. be Conte for identifica- 
tion, he writes us that it is a species of Pityophthoru*, not described. Dr. 
Le Conte adds: " Blanchard writes that Hypophfaus tenuis depredates 
on this species." (Le Conte afterwards identities it as probably P. 
pubervlus,) 
44. Xyleborus imprcssus Eichhoff. 
Le Conte states that this species occurs in Georgia under pine bark. 
45. PlNK TIMBER-BEETLE. 
Gnathotrichus matcriarius (Fitch). 
Order Coleoptkka ; family Scolytid.k. 
In the interior of the sap-wood, mining slender straight cylindrical burrows in a 
transverse direction, parallel with the outer surface, from which very short straight 
lateral galleries branch off at right angles above and below, a rather slender cylin- 
drical black shining bark-beetle, 0.15 long, with pale dull yellow legs and antennas, 
the forepart of its thorax and of its wing-covers tinged with reddish yellow ; the 
thorax equaling two-thirds the length of the wing-covers with a small elevated 
tubercle in the middle, forward of which it is rough from minute elevated points: 
the wing-covers with rows of minute punctures, their tips rounded, the upper part of 
the declivity with a shallow longitudinal depression or groove along the suture, 
forming a slight notch. 
" The insects belonging to the genus Tomicus and kindred genera of the 
same family by their habits divide themselves into two distinct groups. 
The larger portion of them reside in or immediately beneath the bark 
of different trees, and are currently termed bark-beetles. But this 
designation is inappropriate for another portion of them which dwell in 
the interior of the wood, and there excavate their galleries. The name 
timber-beetles appears to be the most appropriate for these. Another 
point in which, from the observations of M. Perris, these two groups 
appear to differ in a remarkable manner is the relative numbers of the 
two sexes. With the bark- beetles there are commonly several males in 
company with but one female, and the former appear to perform the 
chief part of the labor in the excavation of their galleries. With the 
timber-beetles, on the other hand, the females are much the most numer- 
ous, aud probably mine their galleries without any assistance from the 
other sex. M. Perris states of one of the species that upwards of fifty 
females were met with in the burrows they had excavated without a 
single male being found there. 
