50 
Indiana University Studies 
known to occur with the European Neuroterus saliens 
(Kollar) and with the American Andricus saltatus Ashmead; 
in all of these cases the gall is separable from the leaf, small, 
thin walled, and entirely hollow except as filled by the con- 
tained larva, and probably these are all the conditions nec- 
essary to produce a “jumping gall”. 
The gall of the winter generation does not appear until 
early in the fall, maturing the very last thing before it falls 
to the ground; this is true for the undescribed Indiana, Q. 
alba variety, for the Texas texanus, and for the California 
saltatorius. The galls usually fall from the deciduous leaves, 
being easily detached, and lie on the ground over winter. 
They are more often permanently affixed to evergreen leaves. 
The insects emerge rather late in the spring. This agamic 
gall, of at least some varieties, appears to be greatly dependent 
upon the moisture of the ground during its final development, 
and it is consequently hard to rear the mature gall wasp, 
altho hymenopterous parasites are always reared in abun- 
dance. The alternate generation is not connected by exper- 
imental data, but incomplete observations on the California 
(and Texas?) variety indicate that the summer form occurs 
in a nearly identical gall also located on the leaf. This alter- 
nate gall appears late in the spring; insects, perhaps only 
agamic females, emerge late in the summer or early in the 
fall. It may be that both generations in this species are 
agamic (see saltatorius), and if this is definitely proved, it 
will be of considerable interest as the most specialized type 
of reproduction in the genus. This might be expected in the 
more specialized species, saltatorius and umhilicatus, rather 
than in others of the subgenus. This heterogeny further 
differs from that known for related species in having the 
dates of development and maturity of both generations later 
in the year. 
Saltatorius is closely related to but more highly evolved 
than most other species of this subgenus. The galls show 
considerable specialization in being so highly separable from 
the leaf, and in being monothalamous, but I question whether 
the definite form indicates anything more than a simple larval 
cell. Wells (1921) shows a larval cell quite distinct from 
the wall of this gall; this may be true for a histologic exam- 
ination at certain stages, but at least the mature gall does 
