The author has collected this interesting gall at Gypsum, Ohio, in August. Many of them measured 5 mm., not including the radiate, bract-like processes borne on the flaring rim of the gall. The galls bear an evanescent thin disk of tissue on the distal, central region, which is clear brown in color and bears erect scattered trichomes. The underlying surface of the gall or the outer convex part is perfectly smooth. The origin of the apical, brown disk is problematical; from the material at hand it appeared as if the rim of the gall had developed by pushing out beneath the original apical tissue. After the disk falls, only a minute dark spot marks the apex of the gall. The surface of the under half of the gall, below the flaring, lacerate rim, is more or less pubescent.
Chamber comparatively large; walls thin.
This very striking gall has thus far only been collected by Mr. Sears and myself, both times in northern Ohio and occurring on H. ovata.
Some specimens, all occurring on the same leaf varied in that they were not so depressed (almost sub-hemispheric) and had the rim strongly inturned against the very convex distal half of the gall.
Sears, Ohio Nat. 15:380. 1914.
33. Cecidomyia? sp.
On leaf, blister-like, irregularly circular in outline, 2½-3½ mm. diameter, ½ mm. thick. Extends above and below about equally. Sometimes a slight central nipple is formed below. Greenish to brownish with discolored margin.
Collected in Vinton County, Ohio, on H. cordiformis.
Probably same as Felt’s “Leaf blister gall, irregular, dull greenish or black margined with small nipple. Diameter 3mm.”
This type of gall is so different from all the other cecidomyid forms that it is doubtful if it is a member of that group. It may possibly be an immature or small Phylloxera gall. The writer found white larvæ within his specimens, but was unable to determine them as cecidomyid larvæ. This gall is thus introduced here, provisionally.