Quarterly Journal of Conchology. 295 



Pupa, 3 of Ciauulia, and 4 of Craspcdopoma. The extra 

 Madeiran distribution of some of these has formed the subject of 

 a paper by the Rev. R. B. Watson in the 1876 volume of ''The 

 Journal de ConchyHologie." Mr. Watson enumerates 28 species 

 as common to Madeira and other locahties, of which 25 are found 

 in Europe, and also for the most part in some of the other 

 Atlantic Islands, whilst H. paupercula occurs in the Azores and 

 Canaries, H. ariiiillata in the Azores, and Vitrina Teuerijfce in the 

 Canaries. 



It maybe remarked how this proportion of indigenous species, 

 of species common to two or more archipelagoes, and of European 

 shells (the latter chiefly introduced) bears out the theory of the 

 separate origin of the different groups of islands. Had they ever 

 formed part of an Atlantis, we might have expected to find a large 

 proportion of shells common to all the groups, some few peculiar 

 species in each, and a few common to the Atlantis and Europe. 

 Instead, we find in all the groups, except the Azores, a vastly pre- 

 ponderant number of purely local forms, \ery few common to two 

 or more groups, and a certain number of European shells of wide 

 distribution, many probably introduced by human agency ; and, 

 with regard to the Azores, the preponderance of European forms 

 is due rather to the poverty of the local fauna than to an absolutely 

 greater number of introduced species. The most characteristic 

 Madeiran groups are Helix s.g. Leptaxis (9 species), lanulus (3), 

 Actinella (17), Octephila (22), Craspedaria (2), Flebecula (5), 

 Tech/la (11), Lanipadia (i), Crenea (2), Cionella (11), Pupa s.g. 

 Charadrohia (14), Erynia (5), Craspedopoma {^). 



We may state here, once for all, that it is impossible for us 

 to enter upon the subject of the detailed distril ution of species 

 in the separate islands of a di\ ision without extending this paper 

 to an inordinate length. 



C. The Canaries. Until a few years ngo these islands were 

 comparatively unkno\\n, but recently the principal inlands ha\e 



