BARK BEETLES OF THE GENUS HYLASTES 13 
all cases occur in lot series with several or many intermediate or 
typical specimens. Intermediates between the two extremes repre- 
sented by scaber and swainei are to be found in any large series col- 
lected at any locality from Maine to Texas. The writer has little hesi- 
tation in placing swaine? as a synonym of porculus. 
HYLASTES NIGRINUS (Mannerheim) 
Hylurgus nigrinus Mannerheim, 1852, Moskov. Obshch. Isp. Prirody, Otd. Biol. 
Biul. (Soe. Nat. de Moscou, Sect. Biol. Bul.) 25: 356. 
Hylastes nigrinus Leconte, 1868, Amer. Ent. Soc. Trans. 2: 174; Chapuis, 1869, 
Synop. Scolyt., p. 18 (extract from Soc. Roy. des Sci. de Liége Mém. (2) 8: 
226; Leconte, 1876, Amer. Phil. Soc. Proc. 15: 888; Hamilton, 1894, Amer. 
Ent. Soc. Trans. 21: 36; Swaine, 1918, Canada Dept. Agr. Ent. Branch Bul. 
14 (2): 78, 79. 
Female.—Dark piceous brown to black, 4.1 to 4.9 mm. long, about 2.96 times 
as long as wide. 
Frons moderately narrow between eyes, frontal rectangle about 1.13 times as 
long aS wide, nearly black, with epistoma slightly lighter; epistoma broadly 
and deeply impressed at each side; median carina usually confined to epistoma 
but occasionally extending nearly to central pit; epistomal margin nearly black, 
liplike, median lobe short, moderately broad, broadly excavated, with free end 
emarginate; arcuate transverse impression moderate at sides, deepest in middle 
line, often forming a pitlike depression; surface subopaque, moderately finely, 
densely, somewhat roughly punctured, feebly granulate at sides. Eye rather 
finely granulate, less than twice as long as wide, much wider above. Antenna 
with first joint of club as long as others combined. 
Pronotum slightly but distinctly narrower than elytra, about 1.12 times as 
long as wide, widest just in front of middle; posterior outline feebly bisinuate ; 
posterior angles only slightly rounded, sides nearly straight behind and diverg- 
ing slightly to about middle, then arecuately narrowed to broadly rounded front 
margin; surface feebly shining to subopaque, with moderately coarse, close, 
deep punctures, somewhat irregular in size (closer than and not so coarse as 
in porculus), distinctly smaller and denser in front and somewhat smaller, 
closer, and rougher (subgranulate) at sides; median line narrow, weakly ele- 
vated, sometimes nearly lacking. 
Elytra wider than pronotum, about 1.9 times as long as wide; sides nearly 
straight and subparallel on anterior two-thirds, then gradually, arcuately 
narrowed to the narrow but broadly rounded apex; striae and interspaces 
subequal in width; striae mcderately impressed, more deeply so behind on disk 
and on declivity; punctures coarse, deep, and close, smaller on sides and de- 
clivity ; interspaces moderately convex on disk, strongly convex on declivity, 
nearly flat on sides, rugosely granulate-puncitate on disk and sides, more strongly 
granulate on declivity; ninth interspace strongly elevated behind; pubescence 
short, fine, sparse on disk, mostly wide and scalelike and more abundant on 
declivity. Last abdominal sternite convex, moderately rounded behind, rather 
coarsely and roughly punctured, with rather short, fine hairs. 
Male——Similar to female in size and proportions, but more coarsely sculp- 
tured; last sternite of abdomen shorter, more broadly rounded, subtruncate 
behind, broadly impressed in median line, with finer, denser punctures and 
longer, yellowish hairs in impression. 
Remarks—The series studied, consisting of more than 100 speci- 
mens, shows considerable variation, not only in size and sculpture but 
in the shape and width of the pronotum and the apex of the elytra. 
However, there is by no means so much variation as in the closely 
allied eastern species, porculus. Series from various localities con- 
tain specimens that have the pronota notably narrower, with the 
widest point near the bases and the sides feebly arcuate. 
Hylastes nigrmus is distributed from Alaska to California and 
eastward to Idaho. It is very common in Washington and Oregon. 
Host records include Douglas fir, true firs, spruce, pine, and western 
hemlock. 
