12 GALLS. 



Foerster. Hymenopterologische Studien, ii ; his 

 Beitr. zur Monographie der Pteromalinen, 1841. 



Nees ab Esenbech. Hymen. Ichneumon, affin. 

 Monogr., vol. ii (1834). 



Thomson. Hymen. Scan., iv and v. 



Thanks to the admirable monographs of Mayr on 

 the Torymina, Olinx, and Eurytoma, the identification 

 of these groups is rendered comparatively simple ; but 

 some of the others, and more particularly Pteromalina 

 and Tetrastichus, are in the utmost confusion. The 

 number of Ichneumonidse and Braconidse parasitic on 

 the CynipiddB is comparatively small. 



Galls. 



All the galls of the Cynipidse are completely closed, 

 none of them being open as we find them in Hemip- 

 tera and some Diptera. As regards texture and con- 

 sistence they may be divided into the soft and succu- 

 lent, and the hard and woody ; as regards position on 

 the plant they fall into two groups : first, those which 

 are entirely external from the plant, being only at- 

 tached to it by a small part, e. g. Bhodites eglanterise ; 

 and secondly, those which are more or less embedded 

 in the plant tissue, e. g. Bhodites sjpinosissimce. Again 

 the galls may have many cells (polythalamous), or 

 have one only (monothalamous) ; but the latter, by 

 the influence of inquilines, may be made polythala- 

 mous. 



Forms and Origin of Galls. 



The forms of galls are endless. They may be 

 round, spherical, lenticular, oval, or perfectly flat. 

 They may be permanently attached to the tree (Cynips 

 Kollari), or, when ripe and the larva at maturity, may 

 drop immediately to the ground from the leaf or bud, 

 or may drop before the larva is fully developed, the 



