$60 



ARACHNOIDEA. 



CASE smaller, appears more confined to the margin of the leaf than in 

 the plum tree, and is more aggregated and velvety. 



Ceratoneon attenuatum on leaves of sloe 



Section of g-all on sloe leaf. 



Nos. Phytoptus pruni (Volvulifex pruni, AmerL; Ceplialoneon pruni, Bremi; 

 Bursifex pruni, Amer.). — %, Leaves of plum tree bearing galls of ditto ; 

 9. Sketch thereof ; 10, Magnified section of gall of ditto, showing in- 

 terior filled with hairs and no mites. 



These are galls like purses, made by Phytopti on the under 

 side of the leaves of the plum tree ; there soon appears on the 

 upper side little purses or club-shaped galls of the size of a hemp 

 seed, on the outside of which grow Phyllerium and Erineum-like 

 white hairs. The top of the gall is red in the beginning ; later 

 it becomes chestnut brown. This Acarocecidium is usually found 

 on the second or third leaf of the twig. Dr. Amerling (" Ges. 

 Aufsatze," p. 159) noticed these galls in Bohemia, but took the 

 gall mites found in them for larvae of a mite, which he named 

 Bursifex pruni. (See also '' Dr. Thomas, 1. c. zi, Bd., 1869, p. 330, 

 No. 2.") 



