370 ARACHNOIDEA, 



CASE PlIYTOPTUS Sp. 



XVII. 



This causes a deformity of some of the lateral twigs and leaves 

 of the aspen, at the beginning of a reddish colour, later, however, 

 spotted with black, very striking, even at a distance. Dr. Thomas 

 (1. c. 33, Bd. 1869, p. 341, Anm. 17) calls them remarkable rollings 

 and crinklings of the leaf. Such lateral twigs are shortened, the 

 leaf-stalk extraordinarily drawn near to one another, and the 

 leaves wrinkled beyond recognition, the edges in various ways, 

 either turned up, wrinkled, or rolled back to the middle of the 

 leaf. On many of these deformed lateral twigs, which are often 

 pyramid-shaped, one or more normal leaves may be found at 

 the base ; howxver, almost all the leaves on such a lateral twig 

 are attacked. This bare Acarocecidium is full of numerous 

 Phytopti. 



On the Walnut. 

 Phytoptus Sp. 

 Numerous brownish-red galls, about one millimetre in diameter, 

 are scattered in the parenchyma of the leaves, and project on 

 both sides ; beneath they are somewhat more wart-shaped, so that 

 their height is about ij millimetre. The outside is not hairy, 

 rather rough, and uneven, the inside is filled with loose parenchy- 

 matic cellular tissue, in which a gall mite lives in astonishingly 

 large numbers. The entrance to the gall is on the underside bare 

 and narrow. The Phytoptus which lives in this gall measures 

 about one-sixth of a millimetre, and is either of a brownish or 

 yellowish colour. 



Erineum juglandinum, Pers. (Erineum juglandis Ung, Phyllerium juglandis, 



Schleich). 



Oblong, the surface of the leaf strongly raised between the side 

 nerves, underneath a short first white, then brown, Erineum, in 

 which the gall mites live. 



