CATALOGUE OF BRITISH PLANT-GALLS 251 



Sonchus arvensis Linn. 1 12. Com Sow-thistle. 

 Diptera Gregarious circular patches on the radical leaves ; green 

 at first, becoming red or purple, glabrous or glossy. The 

 swelling is the more pronounced on the superior surface. 

 Each gall contains a white larva. M. G. Imago appear- 

 ing in the autumn. (Plate XXXII.) 



Cystiphora sonchi F. Low 880 

 Syn. Ceddomyia sonchi Connold. 

 Connold, Plant Galls, fig. 279. Houard, No. 6100. 



ERRATA 



The galls on Blackthorn leaves described on pp. 94 

 and 197, and figured in Plate XXI., Fig. i, are caused by 

 Eriophyes padi Nalepa, not by Eriophyes similis Nalepa. 

 The galls which result from the presence of Eriophyes 

 similis on Blackthorn leaves are whitish, with an elon- 

 gated hairy aperture (often with purplish margin) on the 

 upper surface of the leaf. 



