1864 .] 
487 
8 . Swamp white oak (q. prinus, var. discolor.) Grail q. petioUcola 
(vernal). It is well described by Osten Sacken, but the author of the 
gall was unknown to him. {Proc. Enf. Soc. Phil. I, pp. 66—7.) Some of 
these galls, when occupying the base of the leaves, reach .60 inch in 
diameter, and produce each 9 or 10 flies, judging from the holes 
through which they have made their escape. 
GtALL-ply, G. q. petioUcola Bassett. My specimens differ from Mr. 
Bassett’s description as follows, with a few additional characters:— 
\st. The face in the living specimen is sometimes rufescent, but in the 
dried specimen it is black and not even “ brownunder a good lens 
it is very finely aciculate, with a flat glabrous carina from the origin 
of the antennae to the mouth. '2nd. The antennae are uniformly pale 
reddish brown or dull rufous, scarcely darker at tip, 13-jointed, the 
last joint nearly as long aS the two preceding ones put together, and in 
two or three specimens showing indications of the normal division into 
two joints, as in some of Mr. Bassett’s specimens. The % antennae are 
15-jointed, 13—15 subequal. 3rf?. Besides the two lateral striae (or 
parapsidal grooves) of the mesonotum, there is in five or six 9 9 a 
distinct central stria reaching halfway from the scutel to the collare, 
and a shorter stria in the other 9 9 and in my % . 4:th. It is only the 
femora and tibiae of the hind legs that are generally dark brown, the 
tarsi of the hind legs as well as the whole of the other four legs being 
pale reddish brown, the tips of all six tarsi brown as described. 5/A. 
The 2nd abdominal joint 9 generally occupies dorsally f but laterally 
only i of the length of the abdomen, exclusive of the peduncle; and 
its dorsal edge describes a circular arc of about 45°. The “ ventral 
valve” is subhyaline, its tip in an angle of 80° or 90°, and with a seti- 
form appendage as long as itself; and the “dorsal valve” projects 
slightly above the dorsal line. The radial area is 2 J—^3 times as long 
as wide. Length S .09 inch, 9 .10—.11 inch. 
One S , nineteen 9 . Bred the end of June and forepart of July 
from galls produced the same year. Mr. Bassett’s remark as to the 
somewhat greater comparative length of the abdominal peduncle in % 
is perfectly correct. 
Guest gall-fly, Ambl^notics ensiger n. sp. ? See below. One % , 
four 9 at the same time with the above, and from July 31 to August 
14 five S , eight 9 . Greatly resembles the gall-fly, but, besides the 
