96 PROCEEDINGS OF THE BRITISH ASSOCIATION. 
Northern Russia, the greater part of the British Isles, and Iceland, and extends 
itself into America in Greenland. The second, Germany (except Austria), 
Holland, Belgium, the south of England, the greater part of Switzerland, and 
northern and central France. The third, south of France, the Peninsula, the 
west of Italy, the western Mediterranean Isles, and extends itself into Africa (in 
Barbary), even to the Canaries, where a more tropical Fauna commences. The 
fourth comprises the east of Italy, Turkey, Greece, Dalmatia, and Wallachia, 
and extends itself to Asia Minor, and probably Syria. The fifth includes southern 
and perhaps Central Russia, extending itself over the Caucasus to Georgia. Be¬ 
sides these divisions, there is a large and important tract of inland country, 
including Austria, Hungary, Styria, Carinthia, and the eastern T^'tol. Through¬ 
out the world, he observed, it will be found that every genus has a generic 
locality, that is to say, that in a certain country its species predominate more 
fthan in any other part of the globe, and the typical forms of each of its groups are 
there represented. In Europe, we have a beautiful instance of this phenomenon 
in the genus Clciusilia , as seen in the fourth division. He observed that each of 
the groups referred to these divisions were influenced to a great extent b}* - five 
modifying causes, viz., 1, soil and rock; 2, mountain ; 3, elevation; 4, sea; 5, 
transportation. The first, or geological influence, is of great importance, so much 
so, indeed, that a malacologist might almost name the structure of a country from 
the land shells inhabiting its surface. The rocks w T hich have most influence are 
those of calcareous structure, and even the different formations of Limestone 
rocks supply localities to species peculiar to themselves. The second, or influence 
of mountain. The former exists in Britain; of the latter he had at present seen 
no instances. The influence of the neighbourhood of the sea is seen in the case 
of certain Helices and Bulimi , which never thrive inland. The fifth is rather a 
class of influences than a single influence, including as it does the effects of Man’s 
agency in the introduction of species, both for domestication or by accident/ as by 
ballast, which at the present moment is exercising a most important influence on 
the British Fauna and Flora; and the effects of natural agency, as in the trans¬ 
portation of species by rivers, &c. The effects of these modifying influences is 
the multiplication of the individuals of a species. There is also a climatic 
influence, which must perhaps be classed along with these, and the result of which 
is the superior development of size and colour in certain species. In conclusion, 
the author called on the naturalists of Great Britain to assist him in preparing 
data for the investigation of the distribution of land and fresh-water Mollusca in 
this country. For this purpose, he exhibited a map of Great Britain and Ireland, 
divided into districts, drawn up by Mr. Brand, of Edinburgh, for the Botanical 
Society of that city, with a view to the classification of the distribution of British 
plants. It is constructed on the most philosophical principles, and does the 
