1865.] 357 



was not quite sure which. These gall-flies altogether resemble C. tumi- 

 fica, and I do not doubt of their identity. Some of the specimens had 

 the whole mesonotum reddish, and only a broad stripe in the middle, 

 not reaching the scutellum, brown. As among these specimens there 

 were several males, I give here their description. 



£ 0.06 — 0.07 long; altogether black, except the antermte, which are brownish, 

 and the feet, which are like those of the £: antennae 15-jointed; third joint 

 elongated, curved; sculpture of the mesonotum exceedingly fine, almost im- 

 perceptible, and for this reason the mesonotum moderately shining ; the two 

 smooth lines between the parapsidal grooves are perceptible : abdomen very 

 sruall in comparison to the body; wings like those of the J; veins dark brown. 



G. modesta and G. tumifica are very closely allied and their galls 

 also; both differ principally in size. The insects differ, moreover, by 

 the number of joints of the 9 antennae, by the coloring of the latter, 

 which is a uniform brownish-yellow in G. modesta, whereas the antennae 

 of tumifica are brown at the tip ; by the coloring of the mesonotum of 

 the female, which is uniform brown in G. modesta and is more or less 

 mixed with reddish in C. tumifica. These two species, with G. q. nigrse, 

 form a distinct group, having the structure of their galls, the absence 

 of an areolet, the sculpture and coloring, etc. in common, and it is pro- 

 bable that the % of C. modesta is, like that of the two other species, 

 distinguished by its small size and dark coloring. It is also worthy 

 of notice that the ovipositor of G. nigrse, and especially of G. tumifica is 

 very often entirely exserted from the sheath, in the shape of a large, 

 free spiral, outside of the abdomen. I do not know how to explain this 

 peculiarity, which I have not observed so constantly in any other species. 



35. C. modesta 0. S. Proc. etc. T. p. 65. No. 16. (9 . Q. rubra.) 

 Compare the preceding species. 



36. C. operator O. S. Proc, etc., I, p. 256. ( % 9 ; Q. nigra.) 

 Compare also Bassett, 1. c. II, p. 332. This species has 12-jointed 9 

 antennae; the length and structure of the sheath of the ovipositor, the 

 structure of the abdomen and the neuration of the wings will probably 

 entitle C. operator to become, at once, the type of a new genus. The pe- 

 culiar character of the neuration (absence of the branch of the subcostal, 

 running towards the margin of the wing) it has in common with ( '. 

 similis and G. quercus phellos. Mr. Bassett has observed galls similar to 

 those of C. operator O. S. (Q. nigra), on Q. ilicifolia and Q. palustris. 

 He communicated to me the insects obtained from these calls, and I can- 

 not discover any important difference, except that the hind tibiae of 

 the specimens obtained from Q. ilicifolia were not infuscated, and the 

 subcostal as well as the transverse veins, were somewhat darker. 



