1 l(j Proceedings of the British Association. 



3. Tertiary. 



4. Saliferous. 



5. Slates. 



6. Granite and Gneiss. 



Mr. Forbes noticed, that in certain cases climate neutralized the in- 

 fluence of the rock, and vice versa ; and instanced Guernsey, as a locali- 

 ty where the neutralization of geological influence by climate is positive, 

 and Shetland, where it is negative. Under the head of secondary influ- 

 ences, Mr. Forbes considered the effect of the neighbourhood of the sea — 

 the neighbourhood and elevation of mountains — the presence of woods, 

 and the influence of the various trees found in them — the influence of 

 water, especially of artificial water, as canals, and the vitiation of the 

 Fauna by the agency of man, as in the case of the transportation of 

 species by ballast, &c. Instances were given of the effect of these various 

 influences in Britain, and the comparative effect of each on the existing 

 Fauna considered. It was stated, that, in our country, the influence of 

 elevation is always negative, but that in many other countries it is po- 

 sitive. It was shown also, that fossils, especially those of the newer 

 pliocene strata, materially influence the Fauna in certain localities. 

 A detailed view of the distribution of the species was then entered into. 

 They were arranged under ten districts, viz. 1. the Channel Isles; 2. 

 S. E. of England ; 3. S. W. of England ; 4. N. E. of England ; 5 N. W. of 

 England ; 6. S. of Ireland ; 7. W. of Ireland ; 8. S. of Scotland ; 9. W. of 

 Scotland; 10. Shetland Isles. Tables were shown, exhibiting the rela- 

 tive importance of the various influences in each, and the causes of the 

 presence of the more local species were considered. Helix revoluta and 

 Helix naticoides were mentioned as additions to the British Fauna from 

 Guernsey. The researches of Mr. Alder, of Newcastle, and Mr. Bean, 

 of Scarborough, were particularly alluded to, and much novel informa- 

 tion contributed by those gentlemen mentioned. Mr. Forbes then con- 

 sidered the distribution of the principal British species in foreign 

 countries ; and in a table exhibited a comparison between the principal 

 published lists of Europe. The southern countries present much fuller 

 lists than the northern. In the number of native species of helix, Eng- 

 land exceeds Scandinavia by seventeen species, and Brabant by fifteen, 

 but yields to the other European lists of equal importance, especially 

 those of the southern countries of Europe. France exceeds Britain by 

 no less than forty-one species. The Helix fusca, the Clausilia Rolphii, the 

 Pupa anglica, and the Lymncea involuta, of Thomson, were mentioned, as 

 species, only found in Britain. Many remarkable instances of extensive 

 distribution were mentioned. The common snail, Helix aspersa, is equal- 

 ly common throughout southern Europe, and is found also in parts of 

 Asia, Africa, and North and South America ; and the edible snail is nearly 

 as widely distributed. The Succinea amphibia is very widely spread over 

 the world, being found throughout Europe, from Archangel downwards, 

 in North America, and in North and South Africa, as far as the Cape of 



