80 



BRITISH OAK GALLS. 



in situ, for some months firmly rooted in the twig, 

 affording " an instance in this of what is frequently 

 found to l)e the case, that when an inquiline lays its 

 egg in an immature gall the growth of the gall is 

 altered with the death of the original larva, and 

 becomes pathological " (' Alternating Generations,' 

 p. 44). 



Although the sexual generation is so plentiful, 

 collaris is somewhat uncommon and does not appear 

 to have been often found by the collector. 



Fig. 8. — Galls caused by Aphilothrix collaris. a. In situ, nat. size. 

 B. Enlarged x 4. c. Some leaf scales removed x 4. In part after 

 Mayr. 



It is sometimes embedded in the leaf scales of A. 

 fecundatrix. 



Aphilothrix corticis, Linn. 

 (Plates XIX, XXII, div. A.) 



Cyni2)s corticis, Hartig, Sclienck., Kalt., Kirch., Thorns. ; Andricus 

 corticis, Mayr, Camerou, Mosley ; Aphilotlirix corticis, Adler, Majr, 

 Lieht., Fitch, Ormerod. 



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



Position of gall. — In the bark, iu the rim of a callus, in axil of 

 a Ijranch. 



Manner of growth. — Glabrous, glossy, gregarious, conglome- 

 rated, embedded. 



Colours. — G-reenish-yellow, yellow suffused with pink, purple, 

 brown. 



Average dimensions of a mature specimen. — Depth, 

 10 mm. ; breadth, 4 mm. ; girth, 12 mm. 



May be sought during any month of the year. 



Growth is complete by the end of May. 



The typical condition of the gall is unilocular and unilarval. 



