96 
Male.—Length 6.5 mim.; structurally for the most part as in female; 
head not narrowing back of compound eyes; antenna nearly as long 
as body of the insect, strongly tapering, robust, and somewhat com. 
pressed basally; procidentia broad, rounded, not projecting more than 
half its width, strongly keeled. Color black, shining; apex of clyp- 
eus, labrum, palpi, angles of pronotum, tegule, legs except bases of 
coxe, venter, and most of tergum yellowish ferruginous; base of the 
dorsal segments, particularly of the first and second and fifth to seventh, 
brownish black; in some specimens all the segments are brownish black 
basally; tips of posterior tarsi and sometimes extreme tips of posterior 
tibia infuscated; antenne reddish brown; wings hyaline, costal veins 
pale, stigma and veins otherwise brown. 
Four females and five males. Montana. (Coll. Am. Ent. Soc.) 
5. Pachynematus extensicornis Norton. 
1861. Nematus extensicornis Norton. Proc. Bost. Soc. Nat. Hist., vii, p. 159. 
1864. Nematus marylandicus Norton Proc. Am. Ent. Soc. Phila., 111, p. 7. 
1867. Nematus extensicornis Norton. Trans. Am. Ent. Soc.,1, p. 117. (Cat., ete., 
p- 59.) 
1867. Nematus marylandicus Norton. Trans. Am. Ent. Soc.,1, p.197. (Cat., ete., 
Pp. 59.) 
1867. Nematus awreopectus Norton. ‘Trans. Am. Ent. Soc., 1, p.219. (Cat., ete., 
p. 81.) 
1878. Nematus extensicornis Provancher. Nat. Can., X, p.54. 
1883. Nematus extensicornis Provancher. Add. Faun. Ent. Can. Hym., p. 185. 
1891. Nematus marylandicus Riley and Marlatt. Insect Life, Iv, p. 174, fig. 14. 
Female.—Length 7 to 8.5 mm.; very robust species; abdomen particu- 
larly broad; head very much enlarged back of compound eyes; clypeus 
very shallowly excavated, lobes short, rounded; frontal crest and sides 
of ocellar basin strongly and distinctly defined, the former very minutely 
notched; antennal fovea extending laterally over bases of antenne; 
antenne moderately slender, tapering, joints distinctly defined, 1 and 
2 equal; second recurrent vein interstitial with second transverse 
cubital; third cubital cell two and one-half times as long on lower mar- 
gin as wide at base; discal cells of hind wings long, narrow, upper 
usually exceeding the lower; stigma rather broad, oval, not tapering 
more at apex than at base; sheath moderately broad and thick, ob- 
liquely truncate, upper edge nearly straight; cerci rather long, not 
tapering; claws with a very minute inner tooth, about 4 of length of 
claw from apex. Color resinous or sulphur yellow; antenne, small 
spot including ocelli, stripe on lateral lobes of mesonotum, spot on 
either side of and on base of scutellum, metanotum, tergum except 
narrow lateral margin and the two terminal segments, and sheath 
brownish black; bases of posterior coxe, apices of their tibiw and their 
tarsi, infuseated. There is ordinarily a faint trace of a black stripe 
on the middle lobe of the mesonotum, and in light specimens the black 
markings of the mesonotum are nearly obliterated, and the abdomen 
