308 THE CANADIAN ENTOMOLOGIST 



anteriorly. Anterior parallel lines very delicate. Lateral grooves 

 fine. Pleurae black, subopaque, rugosely punctate with a shining, 

 smooth or almost smooth area. Scutellum black, rugose and 

 without basal fovea. Abdomen black, smooth, shining, with the 

 ventral sheath extending slightly beyond the tip of the abdomen. 

 Legs rufous. Wings dusky hyaline with the cubital and radial 

 cells yellowish brown and a slight cloud of this colour in the large 

 terminal area. Veins brown. Radial area closed on the costa. 

 Cubitus distinctly continuous. Areolet distinct. Length 2.50-3 

 mm. 



Male.— Colour of the female. Antennae 15-jointed. Wings 

 somewhat less infuscated in the cells. Length 2-2.75 mm. 



Gall. — (Plate IX, Figs. 13, 14). On the tips of the twigs of 

 Rosa nntkana. Polythalamous. A rounded, hard and woody 

 gall densely covered with long, green filaments forming a moss- 

 like mass as in Rhodites rosce, and strongly concave at the place 

 of attachment. Diameter 17-38 mm. 



Habitat. — Corvallis, Oregon. (B. G. Thompson). 



A number of galls of this species were sent to me by Mr. 

 B. G. Thompson, collected December 10th, 1916. At first I con- 

 sidered them to be Rhodites rosce Linn. But when the flies began 

 to emerge (indoors) during the latter part of February until about 

 the middle of March, I found that they were different from 

 R. rosce in sculpture and colour. The gall, although similar ex- 

 ternally to R. rosce, differs by being more woody inside and strongly 

 concave at the place of attachment, being almost like an inverted 

 cup or bowl in shape, while the gall of R. roses, is composed of an 

 agglomeration of hard cells around a branch. Named after the 

 late Homer F. Bassett. 



Explanation of Plate IX. 



Figs. 1- 4 Rhodites oregonensis Beutm., on tips of branches. 

 Figs. 5-6 " " in seed-pods. 



Figs. 7-10 " ashmeadi Beutm. 

 Figs. 11-12 " ostensackeni Beutm. 

 Figs. 13-14 " bassetti Beutm. 



