THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[SECOND SERIES.] 

 No. 40. APRIL 1851. 



XXII. — On the Geographical Distribution of the Bulirai, a genus 

 of terrestrial Mollusca, and on the modification of their Shell to 

 the local physical conditions in which the species occur. By 

 LovELL Reeve, F.L.S. &c. 



[With a Map.] 



The Bulimi are distributed over the equatorial, tropical and warm 

 temperate regions of the globe in assemblages of species, limited 

 in their range, and of very distinct typical character ; and being 

 of sluggish habits with few means of transport, little migration 

 occurs even where there are no such natural boundaries as seas, 

 deserts, or mountain chains. Of the Bulimi known from all parts 

 of the world, the localities of nearly 600 species are now well 

 authenticated. They are all described and figured in the ' Con- 

 chologia Iconica' ; most of them with the particular circumstances 

 of habitation. Their area of geographical distribution lies be- 

 tween 40° S. and 35° N. in the new world, and between 43° S. 

 and 52° to 55° N. in the old world ; — that is, between the south- 

 ern borders of Chili and Texas in the former, and between Van 

 Diemen's Land and Germany, if not Sweden, in the latter. And 

 there is no country within this area of which the genus of snails 

 under consideration does not form part of the zoology. There 

 is one abnormal species, B. lubricus, removed from the genus by 

 British authors, which obtains a more northerly range and a 

 greater elevation in both hemispheres. 



Regarding the differences of form, composition and disposition 

 of colour in the shell, the Bulimi are distributed over this area 

 in seven provinces, comprising about forty typical assemblages 

 of species. Of these three-fifths inhabit the western hemisphere, 

 principally Central America, and two-fifths have a wider range 

 and greater local variety of character, in conformity with the 

 more varied arrangement of the land, in the eastern. Taking 

 the size and substance of the shell at different elevations and in 



Ann. £f Mag. N. Hist. Ser. 3. Vol. vii. 16 



