1S(U.] 51 



;;;ill-Hy of the same kind? I have not been able to investii;ate tliis ques- 

 tion sufficiently. Again, if the same gall-fly attacks different oaks, may 

 it not, in some cases, produce a slightly different gall ? It will be seen 

 below that C. quercns futilis, I'nmi a leaf-gall on tlie white oak, is very like 

 (\ quercns papillafa from a leaf-gall on the swamp chestnut oak; I could 

 Milt perceive any difference, except a very slight one in the coloring of the 

 feet. "Both gall-flies may belong to the same species and although the 

 galls are somewhat different, they are, in some respects analogous and might 

 })e the produce of the same gall-fly on two different trees. 



Some gall-flies appear very early in the season; Ci/nips quercusjxdusfris 

 for instance emerges from its gall before the end tf May; these galls are 

 the earliest of the season ; they grow out of the buds and appear full-grown 

 before the leaves are developed. May not this gall-fly have a second gen- 

 eration and if it has, may not the gall of this second generation be differ- 

 ent from the first, produced, as it would be, under different circumstances, 

 in a more advanced season, perhaps on leaves instead of buds etc. ? 



A remarkable fact is the extreme resemblance of some of the parasitica 

 gall-flies with the true gall-fly of the same gall. Thus, Ci/nipt^ q./utilis 

 O. S.,is strikingly like Aylax? futili)<, the parasite of its gall. The com- 

 mon gall on the blackberry stems produces two gall-flies which can hardly 

 lie told apart at first glance, although they belong to different genera. 



I have said enough to show the great interest of the study of the habits 

 of gall-flies and will conclude now by giving some necessary explanations 

 about the terms used in my paper. 



The terminology of the neuratiou of the wing which I have used, is 

 that of Hartig. I call suhcosfal vein the first longitudinal vein below the 

 anterior margin; its tip, joining this margin, forms an obtuse angle with 

 the remainder of the vein. The radud vein begins at the triangular areo- 

 /'■/ in the middle of the wing and runs obliquely towards the anterior mar- 

 gin, which it reaches about midway between the tip of the subcostal and 

 the apex of the wing. The area enclosed between this vein, the anterior 

 margin and the tip of the subcostal is the nulial area. Sometimes the 

 subcostal, instead of stopping at, or just below, the anterior margin, is con- 

 tinued along that margin till it reaches the tip of the radial vein ; in this 

 case, the radial area is closed. The areolct is connected with the angle 

 or knee of the subcostal by a vein which Hartig considers as a part of the 

 radial vein, (he calls it the lower radius) and which Dr. Fitch calls the 

 srroiid transverse vein. I have used the latter name. This vein is im- 

 portant, as on its length and direction depends the form of the radial area, 

 on which, as we have seen above, is based the division of the Ci/nipidse 

 in two sections. In the first section, the areolet is nearly opposite the tip 



