132 



Indiana University Studies 



at the time of collecting, affected by the season of snow and 

 rain. In spite of this a great number of insects matured in 

 these galls. After a couple of years of drying the galls are 

 still rather porous and more soft than are most galls of this 

 genus. 



This variety is very closely related to variety frequens, in 

 both insect and gall characters. It differs rather distinctly 

 from frequens in color and in having larger foveas. In no 

 case have I found the cynipid fauna of Glenwood Springs the 

 same as that of Manitou on the east of the Divide, nor of 

 Green River, Utah, on the west. The Glenwood Springs 

 Cynipidse are usually closely related to, distinctly intermediate 

 with those from Manitou and Green River. I do not have ma- 

 terial from any other locality of this fauna, and cannot guess 

 at the extent of the area other than to believe it is limited. 



Plagiotrichus per dens (Kinsey) 



FEMALE. — Shows the following characters in addition to those com- 

 mon to all species of the genus: Color largely dark rufous and black; 

 antennae black, only the two basal segments piceous black; mesonotum 

 quite smooth and shining, finely reticulated, sparsely punctate and hairy, 

 more densely punctate and hairy anteriorly; parapsidal grooves con- 

 tinuous to the pronotum, narrow, distinct; median groove just evident 

 for the length of the mesonotum; anterior parallel lines hardly evident; 

 foveas broad, deep, shining, smooth; mesopleurse rugoso-aciculate and 

 hairy at top and bottom, a large, smooth, shining, and naked 

 area centrally; abdomen smooth and shining, naked except for 

 a few hairs latero-basally, posterior segments finely, scatteringly punc- 

 tate; slightly longer than high, second segment occupying about half 

 the area; legs rufous including the coxas, most of the hind tarsi and 

 tibiffi black; areolet moderately large; cubitus just continuous to the 

 basalis but faint there; length 2.0-3.0 mm. 



GALL. — Stem swelling, raggedly split open, containing flattened, 

 seed-like cells. Polythalamous. Up to 13. mm. in diameter by 200. mm. 

 long, averaging somewhat smaller. Within are large cavities, 4 or 5 

 arranged more or less radially about the axis of the stem, and a great 

 many in series along the stem, each ca^dty sector shape, extending to 

 the bark, 10. mm. or less in width at edge. Inserted on the wall of each 

 cavity is a larval cell; each cell is monothalamous, flattened, a somew^hat 

 squared oval in outline, 4. mm. high by 3. mm. wide, broadest at the top; 

 concave at the base with a projecting tongue by means of which it is 

 inserted into the twig; cells smooth, shining, buff yellowish; finely 

 streaked, more or less, vv^ith purplish brown. The cell walls are shell- 

 like, moderately thick, entirely hollow within. At maturity the bark 

 splits raggedly over each cavity, the larval cell drops to the ground, and 

 the affected twigs die. On terminal twigs of Quercus Kelloggii, 



