GALL MITES, 371 



CASB On the Horse Chestnut. 



XVII. 



Erineum .t:scuLi, Endl. (Phyllerium axillare, Opiz.) 



Small, brown, roundish, oblong tufts of hair on the underside 

 of the leaves, in the angles of the nerves. Kirchner described 

 these tufts of hair (" Lotos," 1863, p. 47), but took the gall mites 

 found in them to be the larvae of a mite which he called Phyllereus 

 hippocastani. 



On the Oak. 

 Erineum quercinum, Pers. 



On the leaves of the Turkey oak. Round or oblong, more or 

 less raised portions of the surface of the leaf, of very various thick- 

 ness, and on different places on the leaf, of the same colour as it, 

 or, when older, somewhat yellow or brownish colour. They are 

 to be found on the first leaf of the twig, and are inside, that is to 

 :say underneath, filled with a moderately long but thick growth of 

 hair, white at first, then reddish brown, out of which come five 

 ■different kinds of hair, long, curled, pointed, awl-shaped, and 

 :short thick sausage or club-shaped. In rare cases, little spots 

 of this hairy growth are found on the upper side, without the 

 remarkable raising up underneath on the leaf stalk. On search- 

 ing this deformity, its author was found to be Phytopti, which 

 were here almost of one thickness, cylindrical, and of a pale 

 Svine yellow colour. The Erineum quercinum, Pers., therefore, 

 belongs, like all the other Phylleriacia that have been examined, 

 to the gall mites. It is confined to Quercus cerris ; for trees of 

 Quercus cerris, L. pedunculata, Ehr., and sessiliflora, Sm., were 

 growing close to one another, and this Acarocecidium was only to 

 be found on Quercus cerris. 



On the Beech. 



Phytoptus Sp. 

 Galls resembling little brown tufts of hair in the angles of the 

 ribs, on the underside of the leaf, like those which have been 



