180 THE CANADIAN ENTOMOLOGIST 



distinct from gloveri by venation and larval case. I regret that I 

 overlooked the venation in making the examination for Mr. F. M. 

 Jones, or he might have described this also with his new species 

 tracyi. Prochalia pygmcea is evidently more nearly related to 

 Chalia rileyi Heyl. than to gloveri, where I placed it, hastily as it 

 now appears. Perhaps it is the same. Heyl certs describes rileyi 

 with 10 veins in fore wing, 7 in hind wing. My specimens have 11 

 veins in fore wing, 8 in hind wing; Prochalia pygmcea is said to have 

 12 veins in fore wing, 8 in hind wing. So few specimens of these 

 forms are known in collections that the extent of variation cannot 

 be stated, and I will, therefore, not make a positive reference of 

 pygmcea now, though I think it probable that we have but one 

 variable species in C. rileyi. 



THE GALL PRODUCED BY CYSTIPHORA CANADENSIS 



FELT. 



BY A. COSENS, TORONTO. 



In Vol. XLV, No. 12, of this publication, Dr. E. P. Felt has 

 described a new species of gall midge, Cystiphora canadensis Felt, 

 reared by the writer from galls collected in this locality. The 

 obtaining of a large number of specimens has made possible a 

 fuller description of the gall. 



It is produced on the radical leaves of Prenanthes alba L. or 

 altissima L. As both these species grow in this locality, and only 

 the radical leaves are infected by the midge, it is difficult to decide 

 which species is serving as the host. 



The gall is of the typical ocellate form, with a light yellow 

 centre from 1 — 2 mm. in diameter, surrounded by a deep purple 

 ring, averaging 2 mm. in width, which is bounded on the outside 

 by a much narrower ring of the same shade as the centre of the 

 gall. In immature galls the circle at the centre is green and in 

 some exceptional cases entirely absent. When the galls are formed 

 close together on the leaves, they are often connected by the 

 widening of their outside yellow rings. The concentric rings of 

 colour are much more apparent on the upper than the lower surface 

 of the leaf. 



The galls are frequently so numerous on the leaves as to 

 almost cover them. In one instance forty specimens were found 

 on a single leaf. 



