1864.] 
459 
that of sponglfica from f to If inch in diameter, and that in inanis 
the space between the filaments is empty, and in spongifica is filled by 
a dense spongy substance. May not this last difference, as suggested by 
Osten Sacken, be caused by the different re-action of the two different 
species of oak against the sting of the same Cgnipsf I must confess 
analogy is generally opposed to,the supposition; for the very remark¬ 
able and peculiar galls of Ggnips q. palustris were found by Osten 
Sacken on quercus tinctoria, coccinea and falcata, and 1 have found 
them on trees of quercus tinctoria and imbricaria growing by the side 
of each other with their limbs interlaced, while Mr. Bassett has found 
a similar gall producing a slightly different insect on q. ilicifolia. {Prnc. 
Ent. Soc. Phila, II, 329.)* An observation of Mr. Batzeburgh’s to the 
same effect has been quoted by Osten Sacken {Proc. Ent. Soc. Phila. 
I, 248.) On the other hand an instance is quoted by the same writer 
where somewhat different galls on different oaks produce apparently the 
same species of Cgnips (^Ibid. p. 51.) There is considerable variation 
in the shape of the gall of inanis.^ as in that of sqjongijica., some speci¬ 
mens occurring that are not smooth and spherical but covered with ex¬ 
crescences. I noticed two that grew, not out of the leaf, but out of 
the stem close to the origin of the leaf. 
So far as the identity of the parasites infesting spongifica and inanis 
might be supposed to prove the identity of the two species themselves, 
the evidence is indecisive. I have obtained from both in June a beau¬ 
tiful green Gcdlimome (?), and the chalcidide larva mentioned above as 
found in January in the galls of manis, occurs also in the same month 
in those of spongifica ; on the other hand I have bred from spongifica 
alone a large Dorcatoma (?) with spotted wings and a single specimen 
of a Bracon., and from inanis alone a small Pteromalide, all in June. 
The inquiline or guest gall-fly Sgnophrus? Iseviventris 0. S., also oc¬ 
curs in June exclusively on spongifica. 
Baron Osten Sacken, by the way, remarks that “ respecting the true 
relation of the Inquilinm to the Psenides * * not a single direct obser¬ 
vation seems to be extant, and that the fact of their parasitism is there¬ 
fore merely inferred from the circumstance of their having been reared 
Specimens % 9 obligingly sent me by Mr. Bassett are identical with spe¬ 
cimens bred by myself from q. tinctoria.—March 14, 1864. 
