240 [OctobtT, 



" individual.'" I at least have failed to recognize tliem in the specimens 

 of both forms now before me. 



Still, I cannot but think that the constant and striking dissimilarity 

 of the two forms in their pilosity (especially the $ $ ) and also, as it 

 seems to me, in the normal colour of their abdominal spots, is good 

 enough to justify their separation. In that case, our species should 

 have Curtis's name argentatus restored to it, and mucronatus F. must 

 disappear from the British List. 



The alternative, apparently, is to consider mucronatus F. as a 

 species with certainly two — perhaps three — subspecies, viz. : — 



1. mucronatus, typical (Germany, etc.). 



2 arqentatus (Britain and North France). 



3 (?) treforti (confined to Hungary ?). 



But, personally, I think it would be simpler and more satisfactory to 

 call our insect " argentatus Curtis," and treat it as distinct specifically 

 from the non-British typical *' mucronatus F." 



2. — 0. mandihularis Saunders, etc. {nee J)K\\Voom.) =sericatus Gerst. 



The Oxghelus species which we call mandihularis Dahlb. was intro- 

 duced as British by Saunders in his " Synopsis " from 6 6 onl3\ It has 

 since been taken not unfrequently in several localities, and both sexes 

 are described under the name mandihularis in Saunders's later work 

 ("Hymenoptera Aculeata," 1893). There can be no doubt that it is 

 the species which C. G. Thomson referred to '■'mandihularis Dahlbom," 

 and it is also clear that Saunders accepted the identification chiefly on 

 the strength of Thomson's decision. His frequently expressed extremely 

 high opinion of Thomson's judgment may in this case have been re- 

 inforced by the supposition that a species described by Dahlbom would 

 probably be known to the other great Swedish hymenopterist. 



The species, however, to which v. Dalla Torre, Kohl, and most 

 recent Continental authorities refer Dahlbom's description is quite 

 another insect from that of Thomson and Saunders, and has never, I 

 believe, been detected in this country. It is that which has been 

 described by Wesmael (1852) and Gerstaecker (1867) as variegatxis. 

 The latter very careful and accurate author declared himself unable to 

 identify any species known to him with Dahlbom's very unsatisfactorily 

 characterized species. He was acquainted, however, as it appears to 

 me, quite certainly with the insect which we call mandihularis ; but 

 it seenas never to have occurred to him that it could possibly be the 



