30 HYMENOPTERA. 



ella from Nova Scotia which cannot be separated from 

 examples taken in Scotland ; yet both are much less rich in 

 the colouring of their pubescence than any individuals found 

 in the London district. Perhaps the most widely distributed 

 species of bee known is the Megachile centuncularis ; in the 

 British Museum are specimens from all parts of Europe, 

 including Finland and Lapland ; others from North America, 

 Hudson's Bay and Canada : not the slightest difference can 

 be detected in examples from the above widely distant locali- 

 ties. Osmia hirta, of the European Continent, is found in 

 the Island of Madeira and also in the Canary Islands ; Osmia 

 cenea of this country is also found in the Canary Islands. 

 Nomada ruficornis occurs in this country and in North 

 America. The only species of Bombus from North America, 

 which appears to be identical with the European one, is the 

 JBombus hortorum; this insect was captured by Sir John 

 Richardson, at Lake Winnepeg, on his last Arctic expedition. 

 The Vespa vulgaris of Europe cannot be specifically dis- 

 tinguished from what has been considered to be its American 

 representative. The JPompilus Americanus we have regarded 

 as the American form of the European P.fuscus — not to mul- 

 tiply examples, we will only mention the well known insect 

 Chrysis ignita, the common ruby-tailed fly, which is found in 

 no way differing from British examples, at the Cape of Good 

 Hope. That difference of locality is an index to difference 

 of species, need scarcely be denied; but nothing can possibly 

 be more insecure than building upon such an hypothesis: the 

 knowledge which we have acquired of some species of Hy- 

 menoptera in this country proves that nothing but an inti- 

 mate acquaintance, with variable insects, can enable the na- 

 turalist to distinguish between the variety and the species. 



In support of the above opinion, it is only necessary here 

 to quote a single instance; namely, the Bombus subter- 



