106 THE CANADIAN ENTOMOLOGIST. 



do not interfere with the punctation. There is a very short but broad and 

 smooth groove that begins at the scutellum on the middle of the meso- 

 thorax ; it ends suddenly as a groove, but continues as a faint depression 

 half way to the collare. The parapsidal grooves are fine and narroAv, but 

 distinct. There is a smooth polished line over the base of the wings. 

 Scutellum rugose, round, small. Fova large and deep. Legs rather dark 

 reddish brown. Wings large, hyaline, veins slender but sharply defined ; 

 areolet small, radial area open, cubitus extremely slender in the lower half 

 and colorless throughout. Abdomen polished and shining, ist segment 

 long and more than equalling in length the remaining ones taken together. 

 A few short scattered hairs on the anterior half beneath the wings. Sheath 

 of the ovipositor very short, color at the tip dark yellowish brown, a few 

 very short microscopic hairs at that point. 



Length — body .11, wing .14, antennae .08. 



C. IGNOTA, n. sp. 



Galls : Small oval cells, found singly or in small clusters of from two 

 to eight together on the under side of the leaves of Q. bicolor. They are 

 sessile on the midrib and principal veins, and usually lie in a position 

 nearly horizontal to the surface of the leaf They are at first covered with 

 short woolly hairs, but when ripe become more or less denuded. The 

 naked surface when examined with a microscope shows numerous minute 

 papillae, and between these a fine and regular reticulation. They are .10 

 of an inch in length and . 05 in diameter, and might easily be mistaken for 

 the cocoons of some species of Microgaster. 



About fifteen years ago I found a few of these galls on the fallen 

 leaves of a large oak and also on a small tree a few rods distant. The 

 next year the greater part of the leaves on the large tree were covered 

 with galls, a hundred or more being sometimes found on a single leaf I 

 gathered a large quantity after the leaves fell, and the flies came out the 

 next spring. I have examined this tree every year since and have never 

 found any of these galls, nor have I ever seen them on other trees. 



There are some specimens of this species in the Museum at Cam- 

 bridge, which Dr. Hagen informs me were found on oaks in the University 

 grounds. I examined some oaks of the same species in the borders of the 

 Botanical Garden at Cambridge last fall, and found several species of galls, 

 but none of these. Can it be that the species has disappeared entirely ? 



The flies are all females. 



