137 
In August of 1882 the trees were again examined, but not a single 
.gall was found. The early part of the season had been very damp, 
and this had probably exterminated the mites. 
Phytoptus, sp. 
Produces galls on the leaves of the white ash, Fraxinus ameri- 
cana, Linn. 
Stria from 53 to 58. Feather-like appendage with two pairs of 
prongs. Length .007 inch. The hairs on the underside of the 
cephalothorax are easily seen in this species. 
The gall resembles very closely that on Fraxinus viridis. Like that 
it projects equally above and below the leaf. The upper and under 
surfaces have a slight clothing of white hairs. The walls are thick 
and are produced into the cavity. The height, measuring that above 
and below the leaf, is about .085 inch and the diameter is about the 
same. 
A very peculiar cecidum, quite different in character from the 
above, was also found on the white ash, but no Phytoptus was 
found init. It consisted of innumerable small, deformed leaves and 
twigs which had been prevented from developing by the mites. The 
whole mass dries up and remains on the trees during the winter, 
at that time resembling a fungoid growth. 
Both of these cecidii occurred at Bloomington, Ill., in June, 1881. 
a Phytoptus ulmi, n. sp. 
Produces galls on the leaves of the white elm, Ulmus americana, 
Linn. 
A slender species, with from 67 to 70 striw. Prongs of the feather- 
like tarsal appendage, three. Length of specimens preserved in 
alcohol .17 mm. 
In general form this gall resembles that found on the leaves of 
the soft maple, but it is smaller, more slender and contracts less 
abruptly to the neck. It is from .077 to .09 inch high, and .055 to 
_.06 inch in diameter. It differs from the gall on Acer dasycarpum 
further in having seattered unicellular hairs growing from the outer 
surface. There is a tuft of pubescence over the opening beneath. 
The walls are rather thick, with numerous folds projecting into the 
cavity. The color is at times of the same dark hue as the leaves 
or it may be light yellowish-green. The gall occurs sparingly on 
shade trees at Normal, Illinois, and young forest trees in the neigh- 
borhood of Bloomington are sometimes badly galled. The egg, 
young, and adult of the mite, have been found in the galls in June 
and July. 
Phytoptus, sp. 
Produces galls on the leaves of the heart-leaved willow, Salix 
cordata, Muhl. 
The mite has 65 transverse abdominal strie. 
The gall is a wart-like excrescence sometimes projecting above the 
leaf, sometimes below, and again equally above and below. In some 
