XL 



chain of mountains connecting ours with the Alps and Pyrenees. It 

 is also curious why Vanessa Icevana should be absent from our isles. 

 Its caterpillars live gregariously on nettles, and it has a second brood 

 which was described as a distinct species under the name of Prorsa. 

 It is a species which can well adapt itself to any climate. There are 

 also many insects common to England and America, but none that 

 are peculiar to the two. However amongst plants there are two, 

 Eriocaulon septangulare, which is found in the Island of Skye and the 

 West of England, and Spiranthes vomanzoviana which grows in the 

 county of Cork, both of which occur in North America also and not 

 elsewhere. 1 know it has been suggested these have been accidentally 

 introduced, perhaps through the agency of birds. But why should 

 such be the case ? If we turn to the butterfly world again, we find 

 that one species — Colias chrysotheme — occurs only in a very limited 

 district of Central and South Eastern Europe, but in North America 

 it occurs over a very wide range. Another instance of local distri- 

 bution may be seen in a moth, Acidalia degeneravia, which occurs in 

 the islands of Portland and Corfu. Another moth, Bankia avgentula 

 occurs in the East of England and the West of Ireland but not in 

 the intervening districts. Which is most likely, that insects and 

 plants migrated from Europe to America, or from America to Europe ; 

 from Germany to Britain, or from Britain to Germany ? I think 

 neither, but that the same natural causes which produced certain 

 species in Germany, produced the same in Britain ; and that the same 

 natural causes which prodnced Erebia epiphron on the Alps, also 

 produced it on the Pyrenees, and on the British mountains ; and that 

 their occurrence at these places is not the result of migration. Mr. 

 Bates in " The Naturalist on the River Amazon " tells us he has dis- 

 covered intermediate forms to exist between the Heliconia melpomene 

 of Linnaeus, and the H. thelxiope of Hubner, and consequently, that 

 we have here in the existence of a complete series of connecting links, 

 an actual example in recent times of transmutation of species. If a 

 tendency to variation were a circumstance of very rare occurrence 

 among the Lepidoptera, the discovery would certainly be very valu- 

 able as well as interesting, but we have also cases of climatal changes 

 in our English Lepidoptera. Take for instance Lycarna medon. In 

 specimens from the South of England the spot on the upper wings is 

 black, when it is the Agestis of Huber ; in Scotch specimens it is 

 white, and it is then Artaxevxes of Fabricius ; whilst in the county of 



