36 
Indiana University Studies 
MALE. — Relatively quite similar to the female, colored very largely 
the same, generally a little lighter piceous, the legs lighter in color; 
the eyes only a little enlarged; the third segment of the antenna not 
longer than in the female, not at all curved; abdomen smaller but not 
as small as in Dolichostrophus ; areolet more or less larger than in the 
female. 
GALL. — A relatively simple, slight development of various plant 
tissues; varying between three types: (1) inseparable and polythalamous, 
the gall producing relatively little hypertrophy, irregular in outline, 
and usually covered with normal epidermal tissues without special de- 
velopments, internally more or less solid with tissue; (2) inseparable, 
simple, single larval cells buried in the tissue, entirely hollow, not pro- 
ducing much hypertrophy, covered with normal epidermal tissues with- 
out special structures unless an increased pubescence; (3) separable, 
monothalamous, cells of definite form but simple, without special struct- 
ures unless an increased pubescence, internally entirely hollow; on all 
growing tissues of oaks. 
RANGE. — America, probably wherever white oaks occur. 
TYPE. — Cynips floccosa Bassett Neuroterus (Diplobiiis) verrti- 
carum floccosiis (Bassett). 
This submenus is known from 7 American species, vernus, 
niger, howertoni, verrucarum, saltatorius, floricola, and 
umhilicatus, representing 33 varieties, but these seven species 
should have a total of 370 varieties in the United States, 
estimating from the faunal areas and the hosts involved which 
regularly isolate distinct varieties. The addition of varieties 
from North America beyond the United States, or the dis- 
covery of new species, will still further swell the list. Only 
one new species, a Pacific Coast insect, has been added to 
this group since 1892, the other additions being varieties. Of 
the seven species known, one is confined to the Pacific Coast, 
one to the Southwest, and three to the eastern half of the 
United States, while two occur from the Atlantic to the Pacific. 
The group does not appear to occur in the Old World, where 
the subgenus Neuroterus is, however, closely related. 
Diplobius species are all very closely related, making a 
very compact group. The insects are so similar that in many 
cases it will be very difficult to make determinations without 
examining the galls; the only insect which departs from the 
type is floricola of the Pacific Coast. On the contrary, the 
galls of the several species are quite distinct, and the specific 
classification must be based largely on this physiologic data. 
Varieties of a species are, with only one exception, best dis- 
tinguished on characters of insect morphology, and the galls 
