Descriptions of New CynipidfP 195 



less robust thorax, by its more globose abdoineu, and by having 

 the third abdominal segment densely punctured. 



Described from three males and three females bred from 

 galls collected at Champaign, 111., by Mr. John Marten. Ac- 

 cessions number, 15073. 



A. rufus n. sp. 



While looking through the Laboratory collection for Cy- 

 nipidas I was much interested in finding a vial containing a 

 section of a stem of Silphium laciniatum and a number of two 

 species of Cynipidie bred from it. There was not the slightest 

 indication of a gall upon the stem, and it was found that the 

 flies had emerged from little cells in the pith exactly like the 

 cells in the pithy substance of the galls of A. silpJiii, above 

 described. In company with Mr. C, A. Hart I visited fields 

 where this species of Silphium was growing, and we found that 

 the majority of the stems were more or less infested with cy- 

 nipidous larvas, hundreds of which could, in some cases, be 

 found in a single stem; but in no ease was there any indication 

 of the formation of a gall. An illustration of a stem contain- 

 ing these cells is given at Fig. 4, (PI. IX). After finding the 

 stems of Silphium laciniatum so much infested, we pushed our 

 investigations farther and found similar larval cells abundant 

 in Silphium perfoliafum, S. terebinihinaceum^ and S. iuteffri- 

 folium. Whether the flies when bred from these stems will all 

 prove to be one or the other of the two species here described, 

 cannot yet be told. 



Gall-fly. — Female. — Color, rufous; vertex, mesonotum, 

 and scutellum black ; head and thorax opaque ; length, 3 mm. 



Head and thorax minutely sculptured throughout as de- 

 scribed in the tvvo preceding species, face finely aciculate be- 

 tween eyes and mouth, vertex and the portion of the occiput 

 immediately back of it black, tips of the mandibles infuscate, 

 the remainder of the head rufous. Auteuns 13-jointed, -Ith 

 joint a trifle longer than the 3d, the last joint as long as the 

 two preceding and bearing a connate suture that in some po- 

 sitions makes it appear to be two joints, rufous in color, and 2 

 mm. in length. Thorax: parapsidal furrows extending to col- 

 lar, median groove not quite reaching the two parallel lines from 



