280 CALIFORNIA ACADEMY OF SCIENCES  [Proc. 4TH Sze. 
nests in hollow twigs, but Dr. Williams on the label to the 
specimens of macilentus var. hoodensis mentions their occur- 
rence “under stones’. 
20. Camponotus (Myrmamblys) macilentus jacobensis, 
new variety. 
Worker major. Length 7.5—8 mm. 
Head about one-quarter longer than broad, subrectangular, 
a little narrower in front than behind, with nearly straight 
sides posteriorly and occipital border and the cheeks rather 
convex though feebly impressed near the insertions of the 
mandibles. Upper surface of head convex; eyes large, flat, 
elliptical, their anterior orbits distinctly behind the middle of 
the head, two small ocellus-like pits on the vertex and a 
sharply defined frontal groove extending half the distance 
from the clypeus to the posterior margin. Clypeus suboblong, 
one-quarter longer than broad, nearly as broad behind as in 
front, carinate on its posterior half, with a deep pit at the 
suture on each side in front; its anterior border feebly 
rounded, not produced, distinctly crenulate. Frontal area 
minute and indistinct, transverse, rather deeply impressed. 
Frontal carinze more than half as long as the head behind the 
clypeus, strongly diverging, more than twice as far apart at 
their posterior as at their anterior ends. Mandibles rather 
small, very convex, 5-toothed. Antenne slender, scapes 
curved, slightly flattened at the base, their tips gradually 
thickened, surpassing by a distance equal to their greatest 
diameter the posterior corners of the head. Thorax rather 
short, narrower than the head, laterally compressed behind, 
arcuate above in profile with sharply impressed promesonotal 
and mesoépinotal sutures; pro- and mesonotum slightly flat- 
tened above, epinotum high, in profile with subequal base and 
declivity, the former convex, the latter abrupt, forming a 
rounded right angle with it, straight above and very feebly con- 
cave below. Petiole smail, nearly as broad as the posterior end 
of the epinotum, but only about half as high as the epinotal con- 
vexity, its node broadest above, evenly rounded and entire, 
with moderately acute margin; in profile it is inclined forward 
somewhat and has a convex anterior and flat posterior sur- 
face. Gaster rather long and narrow, with subparallel sides 
