Abstract of Dr. Mayrs Monograph on the Synergi of the 

 Oak-galls : by Francis Walker. 



The history of the inhabitants of galls is less understood 

 than that of other parasitic Hynienoptera, their proceedings 

 hid from sight and their mutual intercourse difficult to 

 discover. But Dr. Map* is now investigating them 

 thorouglily with regard to the oak-galls of middle Europe, 

 and a translation of some of his published observations 

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

 The difterence between galls in close contiguity is remark- 

 able, and it is not known wli ether this difference is effected 

 by the peculiar egg laying 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. 

 Mayr's descriptions he indicates here and there much difter- 

 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. Bcinhardi, S. facialis, and >S'. Tschcki may be frequently 

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

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

 some cases one kind of Synergm inhabits several different 

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

 thereby modified. The three following genera are closely 

 allied and form one group in tlie famil^. 



Si/nergus. 



All the face streaked fan-like. Antennae of the male 

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

 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 



