14 BRITISH OAK GALLS. 



case, except that of Fig. 82, both sections have reached 

 maturity. Each section possesses a larval cell. 



Two or three galls of Anidricus curvator frequently 

 grow together, forming but one cavity, with two or 

 three larval cells. Or the gall may develop near the 

 base of the petiole, and produce a swelling bearing a 

 strono' resemblance to A. iuilafor. Xeurotenis Jxvius- 

 cuius affords some interesting variations, a few of 

 which are represented in Fig. 14, where they are also 

 briefly described. 



Variations ix Size, Texture, Colour. 



Size .- (a) Girth . — The smallest of all known galls 

 is that of Neuroterus minutuliis, Gir. It is not yet 

 recorded for Britain. " It is spherical, 1*2 to 1*5 mm. 

 in diameter, thickly covered with short conic-ovate 

 tubercles, and of a rusty brown colour " (' The Ento- 

 mologist,' vol. X, p. 173). 



To return to British galls. The dimensions attained 

 by Aphilothrix radicis undoubtedly exceed those of any 

 other gall. The largest the author has found was on 

 a very old stump, on June 18th, 1902. It measured 

 32 cm. at its greatest girth. Had it not been removed 

 it would have increased considerably hj the end of 

 August, at which time it would have attained maturity. 

 C. Kollari develops into the largest unilocular gall ; 

 specimens measuring 75 mm. in girth are not un- 

 common (See Plate XXXVI, fig. 1)." The cherry-gall 

 occasionally attains 63 mm. in girth. 



(b) Length. — The genus of Andricus furnishes at 

 least nine examples of galls whose external measure- 

 ments do not exceed 2 mm. in length. Two of these 

 seldom attain that length. Both A. vudus and 

 A. pilosus are normally not more than 1*5 mm. long. 

 The latter species appears to be larger, l)ut that is due 

 to the hairlets with which it is covered. 



The stalked-spindle gall, caused by Aphilothrix calli- 

 doma,fm' surpasses all oak galls in its length. Specimens 



