April 1S92.] 



PS 2 CUE. 



243 



Urbana, 111., common ; Lexington, 

 Ky., (received from Prof. W. B. Stark 

 and also collected by myself) . 



8. On the leaves of Acer sacchari- 

 num. A fine Erineum forming patches 

 of a livid color between the veins on 

 the upper surface. The growths show 

 a tendency to avoid the veins. They 

 may be isolated in patches 2.5 mm. to 

 4 mm. in diameter and of very irregular 

 shape, or they may where common 

 combine and then occasionally occupy 

 much of the surface. On badly infested 

 trees scant growths sometimes appear 

 on the under side of the leaves. The 

 color of most of the dried specimens 

 seen is livid. In very young growths 

 but little of this color is apparent, these 

 being mainly pale brown when dried, 

 probably whitish when fresh ; but some 

 trace of the livid color can be made out 

 in most young growths. A few of the 

 growths seen were more nearly flesh 

 color than livid. 



A variety of this Erineum occurs in 

 which the livid color is almost absent, 

 the dried specimens being of a pale 

 brown color in the largest and oldest 

 growths. Even in this variety, how- 

 ever, close examination with a magnifier 

 shows faint traces of the blue color. 

 In manner of growth the two are alike. 



The hairs are capitate, with short 

 stalks, and excepting for their manner 

 of growth and color, are not very differ- 

 ent from those forming the brown 

 patches on the under side of leaves. 



Fort Mackinac, Mich., (from Prof. 

 Wm. Trelease) ; Temple, N. H., (from 

 Prof. A. B. Seymour). 



9. On the leaves of Acer dasycar- 

 putn. This cecidium is a pouch-shaped 

 gall which develops on the upper side 

 of the leaves. The mite which inhabits 

 it was many years ago described under 

 the name Vasates quadripes, but is a 

 true Phytoptus. The deformations were 

 described by the present writer in the 

 1 2th Report of the Illinois State Ento- 

 mologist (p. 135) as follows: "The 

 form varies to some extent, some of the 

 galls being discoid, or more or less 

 spherical, while occasionally 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 they assume the light green color 

 of the veins and veinlets ; and still later 

 change in many cases to purplish. 

 Toward the end of summer they dry up 

 and become 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 gall is usually 

 indicated by an impression with a tuft 

 of white hairs in the center, which tuft 

 covers the opening into the gall. Occa- 

 sionally the opening and tuft are borne 

 upon a slight elevation. The height of 

 one of the largest galls seen, measured 

 from the upper surface of the leaf, was 

 0.1 inch ; its diameter was 0.13 inch." 



This is one of the most abundant of 

 the mite galls in the Middle states. I 

 have received from both Professors Sey- 

 mour and Trelease specimens collected 

 at Madison, Wisconsin. It is abundant 

 throughout Illinois and Kentucky. 



10. On the leaves of Acer dasycar- 



