1929 ] Four New Forms of Eriophyes 301 
ment, that has been reported many times on Celtis. It has 
been attributed to the work of mites by some reporters and 
to the work of a fungus by others. No mites have ever been 
described from the gall though they were observed to be 
present in the buds. Kellerman and Swingle (1888) first 
observed this gall on the hackberry and attributed it to the 
activity of a fungus, which they described as Sphserotheca 
phytoptiphila, associated with a species of gall mite. Reuter, 
in 1903, cited it as an interesting case of coparasitism on the 
basis of their investigations, while Cook (1904), Chadwick 
(1907), and Felt (1917) considered the mites alone respon- 
sible but did not study the gall or mites. In examinations of 
these galls I have always found an abundance of the mite, 
E. celtis , and usually the mycelia of a fungus as well in the 
swollen buds where the gall formation has its origin. Only 
experimentation will be able to decide as to the part played 
by each of the factors present in these galls. It seems very 
likely that the mites are mainly responsible, since the 
fungus, if it is the one described by Kellerman and Swingle, 
belongs to a group not associated with witch’s broom forma- 
tions. 
The morphological characters of the mites found in these 
deformed buds of C. occidentalis differ quite distinctly from 
those of bezzii described by Di Corti. The body size is nearly 
twice as large, although part of this difference may be attri- 
buted to the shrinkage of Di Corti’s specimens which were 
preserved in alcohol. The shield has a clear design of ridges 
and is more nearly semi-circular than semi-elliptical; the 
sternal ridge is bifurcate, not simple; and the setae are all 
much longer and have different relative lengths. The acces- 
sory setae are present, not lacking as in bezzii. Figure 1 
illustrates the characters that are given in the following 
description of celtis. 
The cylindrical body of the mature female is more than 
four times as long as broad, about 270 microns in length 
and 60 microns in width. The thoracic shield is semicircular 
with three distinct ridges usually in the center field pro- 
jecting above the plane of the shield and giving it a jagged 
anterior border; in the side field a ridge curves back from 
