ill a similar gall, they might as well be taken for the males of the two 

 previous species, as the slight differences they show distinguish them alike 

 from the tlii'ee species of females. 



These diff"erences, (besides their longer and 15-jointed antennae and a 

 smaller abdomen, both being peculiar to the sex) consist, as far as I could 

 perceive, only in the d((rk hroini, almost black, and not rrrf color of their 

 abdomen, in their infuscated hind tibia) and tarsi, in a somewhat deej^er 

 sculpture of tlie thorax and in a slightly more distinct punctatiou of the 

 abdomen. These male ([i/iiipx also resemble the C q. ra'fchs, except that 

 the latter is somewhat smaller and that the spot on its wing is also more 

 small and paler. 



Q. TINCTORIA. Blark ixik. Lanjc. rnund (jnU^ hroad and rounded, (it 

 tlif titj) ; surface smooth and <jJos:ii/ ; sJic// thick; inside, a dense, hroion, 

 sponyij substance surroundine/ tlie kernel. Diameter upwards to an inch 

 and a half. C. Q. aciculata O. S. (Syn. C. confluens Harris ?) 



This gall was communicated to me by Benj. D. AValsh Esq., in Rock 

 Island, 111. 



The specimens which I received from him can at once be distinguished 

 from the gall of 0. q. sj_ton<jijica, by their smooth, glossy surface and their 

 subglobular or short-oval form, their basis being slightly attenuated, their 

 top, on the contrary, being broad and rounded. Otherwise, their thick 

 shell and their dense, brownish spongy substance reminds of C. q. s^iong- 

 ifca. 



Mr. Walsh noticed their appearance in summer (about July). The gall- 

 flies usually remain in the gall through the winter and escape in the spring; 

 sometimes however, especially when the weather in the fall is unusually 

 warm, the flies leave the gall already at that season. 



The synonymy of this species with (K cunfluens Harris, supposed by 

 31 r. Walsh, is founded on the occurrence of their galls at tlie same season, 

 and on the statement of Mr. Norton about the agreement of C. q. acini- 

 latd with the original specimens of C. conjjiiens in Dr. Harris's collection. 

 But if Dr. Harris's gall-fly really lives on the red oak (Q. rubra), its great 

 I'esemblance to C. q. acicidata, occuring on the black oak [Q. fiiicforia) 

 would no more be a proof of their identity, than the great resemblance of 

 C. q. inanis and fsjwnqi/ica is of theirs. The two latter gall-flies, although 

 almost perfectly similar in appearance, occur on different oaks and pro- 

 duce quite different galls. It may be that the true C confluens Harris, 

 although closely resembling C. q. adcidata, produces on the red oak a 



