Abstract of Dr. Maijrs Monograph on the Synergi of the 

 Oak-galls : by FiiANcis Walker. 



The history of the inhabitants of galls is less nnderstood 

 than tliat of other parasitic Hymenoptera, their proceedings 

 hid from sight and their mutual intercourse difticult to 

 discover. But Dr. Mayr is now investigating them 

 thorouglily with regard to the oak-galls of middle Eui'ope, 

 aud a translation of some of liis puljlished observati(3ns 

 may be a help to the knowledge of the British species. 

 The difference between galls in close contiguity is remark- 

 able, and it is not known whether this difference is effected 

 by the peculiar egg hiying of each gall-making species, and 

 by the fluid which accompanies that proceeding. The 

 following notice is limited to the Synergi, which establish 

 their families in the galls, and thereby interfere more or 

 less with the originators of them, though in some galls the 

 Synergi have an outer life in the superficial part, and the 

 gall-makers have an inner life in the central part. In Dr. 

 ]\Iayr's descriptions he indicates here and there much differ- 

 ence in size and colouring, and even in sculpture in one 

 species, and thus the identification of some kinds is diffi- 

 cult. More references can be made to his monograph when 

 the British species are better known ; of these three species 

 S. Reinharcli, S. facialis, and S. Tschcki may be frequently 

 seen, the first in the Devon gall, the second in tlie oak 

 apple, the third in the oak spangle. It will be seen that in 

 some cases one kind of Si/nergus inhabits several different 

 galls, but it has not been ascertained that its character is 

 tliereliy modified. The three following genera are closely 

 allied and form one group in tlie family. 



Si/nergits. 



All the face streaked fan-like. Antenn;e of the male 

 15-jointed, of the female 14-jointed ; third joint in tlie 

 male more or less dilated, in two species tumid. Furrows 

 of the front generally reaching to the side-ocelli, seldom 

 short; prothorax without longitudinal furrows in the 



