186 LAND REGIONS. 



Italy and its islands contained in ISTS, according to M. Pau- 

 lucei, 534 siDccies of land and fresh-water shells, a reiBarkable 

 development of molluscan life. Of these, 230 species are 

 inhabitants of Sicily, including a number of forms special to 

 that island. The Helices are rich in the section Campylsea, 16 

 species, in Iberus, etc.; there are 80 species of Olausilia, and 22 

 of Pomatias. 



The Pontic and Caspian subregions partake in general char- 

 acter with the Italo-Dalmatian fauna, with, nevertheless, a number 

 of special forms in each. The basin of the Danube is characterized 

 by the development of certain t^qjes of fresh-water univalve 

 mollusks, Lithogljqjhus, 3Ielania Rollandri and parvula, 

 Melanopsis. Transylvania possesses a particular form of Olau- 

 silia (Baleoclausilia), of which 5 species are known. In the 

 Crimea are found 9 species of Buliminus, certain localized 

 Clausili^e, etc. The Turkish territory bordering on the Black 

 Sea has T species of the group Pomatia (Helix). Transcaucasia 

 has 160 species of land and fluviatile shells, 61 of which are 

 supposed to be peculiar to the region. 



The great richness of molluscan life in the Mediterranean 

 Region, the abundance of individuals, and the thoroughness 

 with which its localities have been explored, have combined to 

 give it an importance beyond that of any other land region, 

 both in conchological literature, and usually also in the cabinets 

 of collectors. The Helicidte alone will number considerably 

 over a thousand nominal species — some of which, however, are 

 merely races or geographical varieties. Clausilia, with its three 

 hundred species, only finds a parallel in importance among 

 cylindrical, many-whorled forms in the West Indian genus 

 Cylindrella. 



3. Central Asiatic Region. 



The shells of Turkestan, Afghanistan and Thibet, are not well 

 known. These countries have only been partially explored, 

 and the hundred species which have been collected in their 

 extensive territories, scared}^ form a sufficient basis for a 

 scientific estimate of the character of the fauna. Many of the 

 species, of fresh-water univalves especially, are those common to 

 Europe (and in some instances to North America) ; although 

 there are some peculiar forms reported from each of the countries 

 comprising the region. There are no species of Pomatias and 

 but two or three of Clausilia, only one Unio ; but Helices are 

 numerous, belonging mostly to North European groups. It may 

 well be doubted whether this should rank as a distinct region, 

 for it partakes, as far as known, too largely of the characteristics 

 of the Septentrional and Mediterranean Regions. 



