26 
Indiana University Studies 
pronotum narrow, not usually visible from above, laterally somewhat 
rougher than the mesonotum; mesopleurae smooth to finely roughened, 
roughest dorsally. ABDOMEN: Usually agreeing in color with the 
thorax, smooth, shining, naked, shrivelling, the individual segments al- 
most never visible in dried specimens ; smaller to larger than the thorax, 
rounded to triangulate, produced dorsally or ventrally or not at all, borne 
on a usually very short petiole, the hypopygium distinct but not large, the 
ventral spine usually very short, less often moderately small, the ventral 
valves usually toward the vertical, only the very tips ordinarily visible. 
LEGS: Black with lighter joints, to wholly yellow, the tips of the tarsi 
always dark; minutely pubescent, most hairy if the thorax is hairy; 
tarsal claws usually very fine and simple, sometimes of moderate weight 
and distinctly toothed. WINGS: Quite clear, rather long, rarely 
clouded; ciliate, the anterior margin either ciliate or not; veins lighter 
or darker brown, the cubitus and discoideus lighter; areolet large to 
small and closed, placed symmetrically below the apex of the cell, or 
placed asymmetrically to one side along the cubitus ; cubitus usually 
continuous, meeting the basalis at the midpoint except rarely; radial 
cell more or less completely open, almost always long, more or less 
narrow, the terminal portion usually of moderate length, reaching the 
margin; the second abscissa of the radius about straight, slightly curved 
near the margin; the first abscissa straight, arcuate or angulate, usually 
without a projection. LENGTH: 0. 6-3.0 mm. 
MALE. — Not known and probably not existent for a few species; 
in most cases known, then agreeing in color with the female, or the 
legs and antennae are lighter, or most of the body is lighter; eyes often 
more or less enlarged, the cheeks and malar space in consequence re- 
duced; antennae lengthened, usually with an additional segment, the third 
usually not longer than in the female, decidedly larger in a few cases; 
curved or not; abdomen very small, elongate, angulate, moderately long 
petiolate; areolet of the same or of a different size from that of the 
female; radial cell as open as or more closed than in the female. 
GALL. — Relatively simple, with usually a small amount of hyper- 
trophy (or even none) ; often irregular in shape and without peculiar 
structures, but sometimes of definite but simple form with a few, simple, 
special structures; usually polythalamous, in fewer species monothala- 
mous; usually inseparable, in some species separable; the larval cell 
with a distinct but inseparable lining; a single species sometimes affect- 
ing several different plant tissues, s6me species confined to a particular 
part of the plant; the several species affecting all of the several parts 
of an oak; occurring on all species of white oaks, but restricted to 
white oaks. 
RANGE. — Cosmopolitan, wherever oaks occur. 
The summarized characteristics of this genus are given 
in the introductory paragraphs of this paper. The genus 
as here treated has quite the same limits as those given by 
other students of Cynipidse, altho a division into subgenera 
has been introduced. 
