256 THE CANADIAN ENTOMOLOGIST. 



Male. — Length, 5 mm.; not robust, approaching slender ; clypeus 

 much more distinctly emarginate than in female ; character of vertex and 

 antenna? about as in female ; procidentia very short and broad, more than 

 twice as wide as long ; venation and claws as in female. Head, for most 

 part, and thorax and abdomen above, black ; face below antennae white ; 

 most of pronotum, the tegulse and the venter, with legs, resinous-yellow ; 

 pro-episterna, and base of meso-epimera, brown ; abdomen slightly 

 smoky beneath ; posterior tibiae and their tarsi slightly infuscated, wings 

 hyaline, veins brown, stigma and costa hyaline, former darker basally. 



Described from two bred females and two bred males in Coll. of 

 H. G. Dyar. This species is closely allied to brunneus, and was briefly 

 described by Mr. H. G. Dyar (including a careful description of the 

 larva?), from six males and four females under Norton's species, Nematus 

 monochroma, from which, however, jt is unquestionably distinct. The 

 larvae are gregarious edge-feeders on poplar, somewhat resembling the 

 larvae of the common willow sawfly {Fteronus ventralis) in appearance and 

 habit [see Can. Ent., XXVI., page 1S7, 1894]. 



Pachyneviatus gregarius, n. sp. 



Female. — Length, 4.5 mm.; not robust, surface shining; head dis- 

 tinctly narrowing back of compound eyes ; clypeus broadly and shallowly 

 emarginate ; pentagonal area depressed, limiting ridges low, rounded ; 

 frontal crest unbroken, not prominent; antennal fovea shallow; antennae 

 short, slender, scarcely tapering, third joint distinctly longer than fourth ; 

 sheath short, obliquely truncate, pointed at tip ; first transverse cubital 

 hyaline or subobsolete ; upper middle cell of hind wings considerably 

 exceeding lower ; stigma broad, rounded on lower margin, not tapering ; 

 claws with inner tooth remote from apex. Colour brownish-black and 

 resinous-yellow ; antennae, head and dorsum of thorax and abdomen for 

 the most part, sheath and up.per half of meso-epimera, dark brown ; 

 mouth-parts, tegulae, outer one-half of pronotum, legs and venter, together 

 with lateral margin of dorsum of abdomen and terminal dorsal sclerites, 

 yellow ; light area of epimera and pronotum slightly infuscated ; wings 

 hyaline, stigma and nervures light brown. 



Male. — Length, 4 mm. ; structurally as in female, except that the 

 ridges about ocellar basin are more sharply defined ; procidentia narrow, 

 tapering, pointed at tip ; antennae, large spot on vertex about ocelli and 

 extending over occiput, thorax above except pronotum and tegulae, and 

 central dorsal area of abdomen (paling towards tip), brownish-black ; 



