98 BRITISH OAK GALLS. 



When tlie gall is mature the rind dries, cracks, and 

 falls aAvay, leaving the yellowish-l)rown inner layer. 

 If the gall is gathered before maturity, the rind will 

 dry and adhere as a thin skin, so closely as to show 

 the stride beneath it. 



Small birds, principally tits, break open the galls 

 in winter time, and devour the inhabitants. 



This gall seldom occurs singly, i. e. only one on a 

 shoot or twig ; it is characterised by the large numbers 

 clustered together — seventy or more within a linear 

 distance of 7 cm. 



When a great many are crowded on a shoot, they 

 penetrate the zylem so deeply that further growth of 



Fig. 10. — Cialls caused by ApMlothrix Sieholdi illustrating tyi)ical shapes 

 and situations. Nat. size, dele, ad nat. E.G. 



the shoot is prevented. It does not, however, decay, 

 but will remain attached for some time, and, frequently 

 shoots may be found bearing new galls near to those 

 of one and two previous years. 



This gall received its specific name after M. von 

 Siebold, who was one of the earliest to find the galls 

 at Dantziff and Frieburof. 



"& 



Biorhiza aptera, Fabricius. 

 (Plates XXXI to XXXIII.) 



CynijJS quercus terminalis, Fabr. ; Tevas terminalis, Marshall ; 

 Biorhiza terminalis, Mayr ; Cameron. Biorhiza aj>tera, Adler ; 

 Mayr ; Mi'iller : Marshall'. Cijnips aptera, Yahr. 



English name of gall. — " The Root Grail." 



Position of gall. — On roots and rootlets. 



Manner of growth. — Glabrous, sessile, gregarions. coalescent. 



Colours. — Pink, yellowish -brown, red, reddish-brown, chocolate 

 brown. 



