446 
[March 
ripe, and bred from them in all during the month of June, 6 S S and 
about 20 9 9 of spongijica, besides a great number of the Cynipidous 
inquiline or guest gall-fly, Sgnophrus Iseviventris O. S., and of two dis¬ 
tinct species of parasitic Chalcididae belonging apparently to Callimome 
and Decatoma, and a single Bracon very near melUtor Say. Up to 
June 14 all the galls that produced spongijica flies were thin-shelled 
and of the type of the gall q. coccinese,. Such galls were then brown 
and ripe, whereas the more hard-shelled and thick-shelled ones were 
then more or less green and succulent. On June 14th, however, I 
bred a % spongijica from one of the latter description of galls, and 
many 9 9 afterwards from such galls; and 1 found that all the interme¬ 
diate grades between the two types occurred in the galls that produced 
spongijica^ some having a shell no thicker than writing-paper which 
wrinkled and collapsed and shrivelled up in drying, and some a shell 
as thick as ordinary cardboard, so as to retain their plump, apple-like 
appearance under the roughest usage; some again having a terminal 
nipple, some many nipples, and some none at all or next to none. The 
last spongijica. (a S ) came out June 18, and after that date no more 
made their appearance, nor after the last day of June any more inqui- 
lines or parasites except a single 9 Callimome (?) on July 23d. Of 
the whole number of galls somewhere about J remained on hand imper¬ 
forated by any insect, those that were perforated having been from day 
to day picked out and thrown away. About the last of June, the thicker 
shelled galls hiwing now become partially ripe and dry, I gathered 2 or 
3 hundred more from the same locality, selecting of course those which 
had not been perforated by any insect. 
During the month of June I had endeavored to experiment on the 
mode in which these galls are generated, by enclosing the boughs of 
of difierent species of oak with gauze-bags and placing therein freshly- 
hatched specimens of S 9 spongijica. Owing to the mischievous pro¬ 
pensities of certain unknown persons, the only fact I was enabled to 
arrive at was, that this insect when fed on white sugar, which it appears 
to eat freely, lives only 6 or 8 days. 
On July 16th I examined the group of black oaks, from the acces¬ 
sible boughs of which I had sometime before stripped all the galls. 
There were no new galls formed there, neither were there any subse¬ 
quently formed there during the summer. Out of about 16 or 18 galls 
