SPATHEGASTER VESICATRIX. 



135 



the gall formation " ('Alternating Generations,' p. 70). 

 The bud may be axillary on a twig, or of adventitious 

 growth on the bole of a large tree. 



The bud galls are inconspicuous, bursting through 

 the large outer leaf scales only when nearly mature ; 

 a feature in which they resemble S. aprilinus and 

 Aphilothrix alhoimnctata . 



Those on the leaf, although small, are not difficult 

 to find. They are sessile. 



The shape of the gall varies. Some are fusiform, 

 others oval, but the prevailing form is cylindrical, the 

 distal end terminating in curved blunt conical pro- 

 jection. 



The walls of the gall are very thin. The interior 



Fig. 17. — Galls caused by Spathegaster verrucosus. All nat. size. 

 In part after Cameron and Adler. dele. E.C. 



constitutes a large larval cavity, Avithout an inner gall. 

 The exterior consists of a peculiar granular glossy 

 rind, clothed with many minute soft pustules filled 

 with a clear liquid. Adler conjectures this is a means 

 of protection against parasites (/. c, p. 69). 



Spathegaster vesicatrix, Schlechtendal. 



(Plate LV.) 



Spathegaster vesicatrix, Mayr, Fitcli, Ormerod (Miss) ; Netiroterns 

 vesicatrix, Mayr ; N. mmiismatis, Cameron. 

 English name of gall. — "The Blister Gall." 

 Position of gall. — lu the blade of the leaf. 



Manner of growth. — Single, solitary, glabrous, glossy, radiate. 

 Colours. — Pale green, grey, pale brown. 



