50 tub; entomologist. 



more to its association will) that mystical miuibcr tliau any 



aclnal experience : — 



" Of every beast, and bird, and insect small, 

 (Jame sevcua and pairs." — Milton. 



These periods were supposed to be influenced by the eggs or 

 pupae of the species lying dormant; but our knowledge of 

 Colias will warrant us in considering them all as arbitrary 

 and unsupported by facts. We know that many Lepidoptera 

 pass two or more years in the penultimate stale, Bomhycefi 

 especially, and that son)e few take more than one year to 

 complete their metamorphosis. These species are very 

 probably afiecled in their appearance n)eteorologically, as no 

 doubt is Colias; but we want more knowledge of our two 

 species to say that the favourable conditions are this only. 



In 1872 we were astonished by an unusual abundance of 

 Vanessa Antiopa. Of late years we have had many well- 

 attested observations of the migration of butterflies ; and it is 

 this which probably affects the appearance of V. Antiopa, 

 Pier is Daplidice, Argyti Ills Lalhonia (all unusually abundant 

 in the autunin of 1872), and other Lepidoptera, in Britain, 

 Some few find the conditions of their new establishment 

 favourable, and establish themselves; but probably unless 

 strengthened by new recruits every now and again we should 

 soon lose these and other species from the British fauna. 

 C. Edusa has been met with more than once in the English 

 Channel travelling from the Continent. The following is on 

 the excellent authority of Mr. Charles Darwin, when on his 

 'Beagle' voyage: — "One evening, when we were about ten 

 miles from the Bay of San Bias, vast numbers of butierflies, 

 in bands or flocks of countless myriads, extended as far as the 

 eye could range : even by the aid of a glass it was not possible 

 to see space free from butterflies. More species than one 

 were present, but the main part belonged to a kind very' 

 similar to, but not identical with, the common English Colias 

 bjdusay It is these migratory habits and a strong constitution 

 which account for the extended geographical distribution ol 

 Colias. Edusa and Hyale are both common to the three 

 continents of the Old ^Vorld, and very closely-allied species 

 are found, in the New. Although originally an immigrant, 

 from the great abundance and distribution of C. Kdusa in 

 Britain and Ireland, it may now be considered as thoroughly 

 naturalised ;' and the numerous specimens captured last year 

 were doubtless mostly iiritish born. Of these I have seen 

 some Imndreds of speciincns, and they vary in almost every 

 conceivable detail. 



