THE FAUNA OF SCOTLAND. 65' 



in structure, size, and coloration from the other, and inhabit- 

 ing completely different galls. Both groups had been 

 described under different generic and specific names, which 

 had to be revised, and the limits of the genera created by 

 Hartig and Foerster redefined. This needful task has been 

 admirably peiformed by Prof. G. L. Mayr in the two publi- 

 cations noted at foot.* Kegarding the specific nomenclature, 

 it has been suggested (Magretti, Sugli Imen. d. Lomhardia^ 

 (2) p. 6) that in future a compound name should be 

 adopted for the dimorphic species; Biorliiza aijtera, for 

 example, to be called Biorliyzatevsa aj)ter'ininalis. 



Apart from this nomenclature being rather cumbersome^ 

 it really is not necessary, since we recognise that the species 

 is actually dimorphic, and that if we call it by one name — 

 Biorliiza aptera — we mean b}^ that the species in all its 

 forms and phases. I therefore only adopt one name, that, 

 namely, under which the species was first described, whether 

 in the sexual or agamic stage.*|" 



The genera I adopt as limited by Dr. Maj^r, and I have 

 given a synopsis of them as defined by him. I have also 

 given a synoptical table of the galls, which will, I trusty 

 render their identification easy. 



The distribution of the gall-making species appears to be 

 co-extensive with the food-plants ; locally they are affected 

 by the presence or absence (with the oak species) of the 

 kinds of tree on which they flourish best. I do not, conse- 

 quently, think it necessary to state, for the common species, 

 their range over Scotland, when I have clear evidence that 

 they are universally distributed. The parasitic species,. 

 however, are very little known, and I have given their dis- 

 tribution so far as I know it. 



The list of the gall-making species is tolerably complete. 

 With very few exceptions we have all the North-West 

 European species, and all the British except two, these being 



* Die Europaischen Arten der Gallenbewohnenden Cynipiden, and 



Die Genera der Gallenbewohnenden Cynipiden. 

 t It is, however, often a great convenience to call the galls by the 

 names under which they were first described. 



