92 THE REPORT OF THE No. 19 



of its nourishment and becomes whitish and roughened or blistered on both 

 sides. Occurs singly on the leaf of the English Elm {Ulmus campestris). 

 Eare. 



Note. — There is a very similar gall on the Red Elm, but differing 

 in the following respects : (1) It is twice as large ; (2) Its texture is a little 

 thicker; (3) The surface is rough, like the leaf, not glossy; (4) The part of 

 the leaf around the base is quite normal in appearance, showing no signs of 

 being weakened through lack of nourishment or any other cause. Probably 

 the difference in the vigor of the two kinds of trees and in the character of 

 leaf will account for these differences in the galls. 



Hickory Hemispherical Gall (Dactylosphccra hemisphericum) . 



This gall is nearly hemispherical in shape, is formed in the parenchyma 

 of the leaf, and the main part of it projects above the upper surface. It 

 varies in size, being from 4 to 10 mm. in diameter and 3 to 5 mm. in height. 

 The color is iisually pale green, often changing to a reddish shade on most of 

 the upper surface of the gall. After maturity the gall withers and becomes 

 dark brown and dead looking, thus greatly disfiguring the leaf. The upper 

 surface of the gall, before it has begun to wither, is slightly roughened by 

 a few depressions and elevations. The under surface is of a paler color, be- 

 ing greenish-white. It does not project beyond the surface except at the 

 small aperture, which is a slit about \ of the total diameter in length. 

 Both sides of this slit project a little beyond the rest of the base of the gall 

 and are reflexed so as to form a mouth-like structure. The gall is monothala- 

 mous. The walls are nearly 1 mm. thick and are somewhat hard and tough 

 in texture. There may be only one or many galls on a single leaf. In most 

 cases where they are abundant they seem to arrange themselves in rows along 

 the midrib, often two deep on each side. Occurs on Shell-bark Hickory 

 (Carya alba). Common. 



Eriophyidje. 



Buttonwood Gall (Eriophyes cephalamihi) . 



This gall usually has the form of a number of small protuberances from 

 1 to 3 mm. high, which have coalesced at the base into one irregularly shaped 

 cluster. The size and extent of a cluster varies greatly ; sometimes a very 

 small part of the leaf, less than one-eighth in some cases, is affected ; at other 

 times several large clusters are found on the same leaf, and occasionally the 

 whole leaf is covered with galls. The galls are usually of a little paler shade 

 of green than the rest of the leaf, but the top is often reddish in color. The 

 texture is somewhat thicker and firmer than that of the leaf. The under 

 surface of the leaf at the affected part is usually depressed, is rough and 

 covered with a white pubescence. The gall occurs on the Button weed 

 (Cephalanthus occidentalia). Common in Muskoka. 



Ball Gall of tbe -Tune berry (Eriophyes sp.). Plate D, fig. 1. 



This is a small, nearly globular gall averaging about 2 mm. in diameter. 

 It is found either singly or in clusters on any part of the upper surface of 

 the leaf. On the lower surface the presence of the gall is indicated by a very 

 small protuberance which is covered witli a hoary pubescence. The main part 

 of the gall, as seen on the upper surface, is dark brown in color, has a slightly 

 roughened surface and is covered with a similar pubescence to the part on 

 the lower surface. It is monothalamous. The walls of the chamber are 

 thin (about 2 mm. in thickness), firm, and somewhat leathery in texture. 

 The chamber is spherical. The gall is rather broadly attached to the leaf, the 

 constricted part being about § of the total diameter of the gall. It occurs on 

 tlie Tune berry (Amelanchier rofnndifolia). Bare. 



