HACKBERRY PSYLLIDS. 621 
smooth and shining, and occasionally beset with a few scattered hairs; 
the elevated margin is coarsely rugose-plicate, and usually also shining. 
Average diameter of gall, including elevated rim, about 3 min ; without 
the latter, nearly 2 mm . On the under side of leaf it is usually semi- 
globular, entirely sessile, sometimes more flattened, rarely more globu- 
lar and then less sessile. Surface more or less rugose, not shining, 
and covered with long but not densely placed white woolly hairs. 
There is sometimes a small apical nipple surrounded by a slight de- 
pression. Average diameter, 3 mm . Color pale greenish-yellow. The 
walls are very thin, but much thicker than the leaf itself; the roof is 
straight and the cell comparatively large and crescent-shaped in a cross- 
cut. Mode of issuing of mature pupa as in the preceding. 
43. P. celtidis-globulus n. sp. — A gall on the upper side of the leaf 
represented by a very circular hole with vertical walls near the top 
and widening internally; the rim is not thickened, but is vertically 
elevated above the leaf surface around the opening. The walls and 
bottom of the excavation are without decided sculpture and of a lighter 
color than the leaf; the elevated rim is of the same color as and not 
thicker than the leaf. Average diameter 1.75 mm . On the under side of 
the leaf the gall is globular or slightly more pyriform and almost stylate, 
or slightly more flattened and more sessile. There is a larger or smaller 
shallow apical depression without central nipple, but sometimes limited 
by a raised rim. Surface a little shining, finely rugose and not pubes- 
cent, rarely furnished with a solitary hair. Average diameter 3.3 mm . 
I have only a single leaf covered with these galls received from 
Columbia, S. C, collected in the month of September. No imago has 
been reared therefrom. 
This is at once distinguished from the preceding species by the very 
deep vertical impression on the upper side of the leaf and its globular 
smooth form on the under side of the leaf. 
44. P. celtidiscucurbita n. sp. — This gall, on the upper side of the 
leaf, forms a cup shaped impression, deeper than in P. c.-mamma, but 
less deep and with the walls less vertical than in P. c.-globulus ; the 
cavity is also not widened internally. The outer rim is not sharply 
limited and not elevated except in one specimen, where it is thickened 
and bulging as in P. c.-pubescens. The walls and the bottom of the cup 
are not distinctly sculptured and of a greenish -yellow color (in dried 
specimens), the rim being reddish yellow and rugose. Average diam- 
eter, 1.75 mm . On the under side of the leaf it arises from a rather slen- 
der, but not stylate, base and widens gradually to the middle, thence 
gradually narrowing toward apex. When viewed from the side the 
outline of the gall is therefore oval, but the top is always truncate. 
The sides near the top are furnished with short ribs, which are sepa- 
rated from each other by wide shallow depressions; the apex is formed 
by an acute rim, which surrounds a cup-shaped depression varying in 
size and depth according to specimens. Surface neither pubescent nor 
shining, but finely and indistinctly strigose. Color (dried specimen) 
