135 
kind were abundant on the poison ivy at Normal, Illinois, in June, 
1881. A single mite was observed. 
Phytoptus acericola, n. sp. 
Produces galls on the leaves of the sugar maple, Acer saccharinum, 
Wang. 
In five examples of this mite the striz were counted, and in three 
of them numbered 30 and in the other two, 28 and 29, respectively. 
The prongs of the feather-like appendage seem to be three. The 
length is about .0075 inch. This form was found in June both 
among knobbed hairs and in galls on the sugar maple, but there 
appeared to be only one species represented. 
The gall is very slender, tapers to both extremities, and bears a 
strong resemblance in general form to the nail galls described by 
Prof. C. V. Riley from the leaves of Ampelopsis. The walls are 
uniformly thin, and present no internal roughness. The height is 
about .19 inch, and the diameter .045 inch. Phytopti were abund- 
ant in these galls collected at Bloomington, Illinois, June 22, 1881, 
Phytoptus quadripes, Shimer. 
Produces galls on the leaves of the soft maple, Acer dasycarpum, 
Ehrh. 
This is the Phytoptus upon which Dr. Henry Shimer founded his 
genus Vasates. It is a coarsely striate species, the striae numbering 
from 387 to 42. ‘The length is about .008 inch. The tarsal claw is 
slightly curved and ends in an evident knob. The feather-like ap- 
pendage has four pairs of prongs. The color varies from pale yel- 
lowish to light orange. Sexually mature females. the young, and 
eggs occur in the galls in June. 
The galls appear with the unfolding of the leaves in spring as 
slight swellings of the parenchyma, and as the leaf reaches its per- 
fect size they expand usually into top-shaped galls, arising from the 
upper side of the leaf. The form varies to some extent, some of 
the galls being discoid or more or less spherical, while occasion- 
ally two galls have a common neck and opening. At first the 
color of the galls is like that of the unfolding leaf, dull purple or 
green; later it assumes the light green color of the veins -and 
veinlets; and still later changes, in many cases, to purplish. 
Towards the end of summer it dries up and becomes black. The 
outer surface is smooth, but the walls are broadly and irregularly 
impressed, making a very uneven outline. On the under side of the 
leaf the position of the galls is usually indicated by an impression 
with a tuft of white hairs in the center, which tuft covers the 
opening into the gall. Occasionally the opening and tuft are borne 
upon a slight elevation. The height of one of the largest galls, 
measured from the upper side of the leaf, was .1° inch; the diam- 
eter was .13 inch. The galls are attached at the sides of the veins, 
and are so numerous on some leaves as to cover the entire upper 
surface. I have seen trees on which there were very few ungalled 
