Descriptions of New Cynipidce 193 



These galls are very common in the vicinity of Champaign, 

 111., on stems of Silphium integrifolium^ and Mr. Hart had 

 collected similar galls at formal, 111., from S. perfoUatum^ from 

 which flies were reared that were in every way identical with 

 those from galls of the other species. 



Gall-fly. — Female. — Black, head and thorax opaque, ab- 

 domen shining, antennse, except first two joints, spot on man- 

 dibles, and anterior and middle pairs of tibiae, ferruginous or 

 dusky ferruginous. Length, 3-4 mm. 



Head: Face deeply and densely striate, median ridge, below 

 the insertion of the antennae, densely and finely sculptured 

 but not striate; gena3, vertex, and occiput densely sculptured, 

 the sculptures being in the form of minute shining pits, as seen 

 under a power of 70 diameters. Thorax: collar and mesothorax 

 finely and deeply sculptured, parapsidal grooves distinct, median 

 groove broad at scutellum and traceable to collar, lateral 

 grooves distinct, all of the mesothoracic furrows sculptured at 

 the bottom. The two parallel lines running back from the 

 collar appear sniooth and shining. Scutellum bifoveate, 

 coarsely wrinkled posteriorly and finely and densely sculptured 

 throughout, including the bottom of the foveae aud the spaces 

 between the wrinkles; pleurae opaque and sculptured like the 

 mesothorax but less deeply. The sculpturing of this insect may 

 be described as a net-work of raised lines enclosing smooth shin- 

 ing spots. Abdomen piceous black, polished, 2d joint occupying 

 one half of the dorsal surface, 3d joint one half as broad as the 

 second, succeeding joints to 7th usually plainly visible, 4th 

 and succeeding joints finely punctured. A power of 70 diam- 

 eters shows slight punctures on 3d segment also. Antenyio", 

 14-jointed, rufous, except the first two joints, which are usually 

 black, but sometimes inclined to rufous, joints 1 and 2 stout, 

 joints 3 and 4 equal in length, last joint once and a half as long 

 as the preceding, length of entire antennae 2-4 mm. Wings: 

 hyaline, radial cell open, radial nervure reaching costal margin, 

 all the nervures very slender, areolet wanting. The entire 

 insect is very free from pubescence. 



The male differs from the female by being but 2-/ to 3 mm. 

 in length, on account of its smaller abdomen, and by having 



