310 
Psyche 
[December 
The gall of americanus is the one characterized by a mass 
of fasciated foliage tissue that Garman noted. I was not 
able to obtain any of the flower galls described by Felt so 
could not determine if the same variety of mite is respon- 
sible for the two deformations. Large numbers of mites 
were collected from the foliose masses and determined as a 
variety of the typical form first described by Karpelles as 
fraxini but known now as fraxinivorus Nal., since the 
former name had been used by Garman two years prior to 
Karpelles to designate the mite producing capsule galls on 
ash leaves. Figure 4 is a lateral view of the variety ameri- 
canus whose description follows. 
This mite is to be distinguished from the typical species, 
apart from the differences of host and parts involved, by 
the unforked sternum, greater number of striae, differences 
in the relative lengths of the ventral setae, shorter accessory 
setae, and much greater body size. 
The body is long, about 250 microns in length and 55 
microns in width for the female, and has a small cephalo- 
thorax. The thoracic shield is semi-elliptical, smooth, or 
traversed by indistinct longitudinal ridges. The dorsal setae 
arise near the posterior border and are about 30 microns in 
length. The legs are short and slender, the tarsi are longer 
than the tibiae ; the feathered claw is four-rayed ; the bristle 
claw, about 10 microns, is longer than the feathered claw of 
either pair of legs; the patellar setae are about 24 microns 
in length; the inner setae of the tarsi are about 4 microns, 
the outer ones about 25 microns long. The first pair of 
thoracic setae are very short and lie forward of the plane of 
the anterior end of the sternum ; the second pair are median 
in length and lateral to the posterior end of the sternal 
ridge which is not forked; the third pair are the longest, 
about 40 microns. The abdomen has 75-80 rings that are 
tuberculated rather finely on the ventrum but with more 
sparsely distributed tubercles on the dorsum; the last five 
rings are without such tubercles and are longitudinally 
striated ventrally. The abdomen ends abruptly in a short 
telson that bears the very short accessory setae, about 6 
microns, and the caudal setae that are about half the length 
