NORTH AMERICAN HYMENOPTERA. 79 



The larvie are imbedded in this and have no larval cell separable 

 from it. The galls are sessile ou the midvein, on the upper surface 

 of the leaf, and the point of attachment extends along the vein one- 

 fourth of an inch. 



The leaves of the oak are very large, measuring more than six 

 inches in width, and the species is probably Q. crassifolia, at least 

 the leaves agree with the description and illustration of this species 

 as given in Humboldt and Bonpland's " Plantes Equinoctiales." 



9. D. (Callirliytes) Clarkei n. sp. 



Small, black polythalamous galls. The sterile flowers of Q. ilici- 

 folia transformed into galls in such countless numbers as to make 

 the aments look like elongated blackberries. The largest gall I have 

 found measured .11 of an inch in diameter and contained four larval 

 cavities. Most of them are considerably smaller, having from one 

 to three cavities, and measuring from .05 to .08 inch. 



Small as these galls are, and short and early as their season is, at 

 least two-thirds of them contain at this writing (November, 1889) 

 living parasitic larvse. In most cases nearly every flower has been 

 transformed into a gall, though in a few the galls are sparingly in- 

 termixed with the flowers. 



At the time the galls were received, early last spring, no flies had 

 made their appearance, but they came out in considerable numbers 

 during the month of May. They are all females, and are described 

 as follows : 



Gall-flies. — Head, thorax and legs very dark brownish red. The head mi- 

 nutely punctate : antennje thirteen jointed, first joint club-shaped, second very 

 short, oval, third slender and a very little longer than the two preceding; fourth, 

 and remaining, to the eleventh gradually shorter; the twelfth and thirteenth so 

 closely connate as to appear as one very long joint, the stiture only visible in a 

 favorable light, the thirteenth joint long, and with a false suture close to the 

 end; mesothorax finely punctate; two short, parallel lines from the collare, a 

 very .short median line from the scutellum, parapsidal grooves extending from the 

 collare to the scutellum and moderately converging on the latter; line over the 

 base of each wing, all these present, but less prominent than usual; scutellum 

 rugose, fovese present, but very small. Abdomen dark, shining, second segment 

 very long and covering the terminal ones in most dry specimens. Legs more 

 dusky red, and tarsi paler than the parts above, ungues black, one-toothed. 

 Wings hyaline, veins almost entirely colorless ; areolet absent, the cubitus sub- 

 obsolete, radial area open, the second transverse vein ends abruptly before reach- 

 ing the margin of the wing. Length : body, .07 inch. ; wings, .08 inch. ; antennae, 

 .06 inch. 



From Miss Cora A. Clarke, Jarnaica Plain, Mass. 



