COOKE: ON" THE GENUS CLAUSILIA. 259 



relations to Phcedusa, but differing in the keeled cervix (Transcaucasia), 

 Mentissa (peculiar to Crimea), Euxina, with nearly forty species (all 

 Asia Minor, Armenia, Caucasia, North Persia, Syria, to Jerusalem), 

 Bitorqiiata, two species (Syria only). Besides these we have 

 Cristataria, which is almost confined to the limestone of Syria (twenty 

 species are catalogued by Germain 20), Micropontica (Caucasus, three 

 species), which is said by Hesse to have an outlier in the Central 

 Pthodope district (J/, despotina, Hesse), Serndma (five species), the 

 most eastern group of all, which, according to Nagele, just touches 

 the Amanus Mountains of Asia Minor {serrulata, Pfr.) but is 

 characteristic of Armenia, Caucasia, North Persia, and the Elburz 

 Mountains south of the Caspian. Finally, a single species of 

 Hemiphadum [perlucens, littg.) is reported, on Boettger's authority, 

 from Lenkoran in the Talysch district on the Caspian, and also, teste 

 Lindholm, from the Tiflis province. The occurrence of this stray 

 waif of the Phcedusa group (possibly a survival of a once much wider 

 extension) is a very remarkable fact, and it illustrates the tendency, 

 already noticed, of single outlying species of a sub-genus to occur far 

 from the general area of its distribution. The nearest relations of 

 this outlier of the great PhcBdusa section are found in the North-West 

 Provinces of India, and in two species of Hemiphcedusa from Prov. 

 Moupin, East Tibet. 



Northern and Central Asia. — The vast extent of territory which 

 falls under the comprehensive name of Nortliern and Central Asia, 

 and measures perhaps 3,500 miles from west to east, and 3,000 from 

 north to south, appears to be wholly destitute of Clausilia. Further 

 investigation of these regions, where arid and trackless deserts 

 alternate with cold and wind-swept plateaux, may perhaps discover 

 a few stray species, but, so far, the evidence, which is not scanty, all 

 tends in the opposite direction. 



No Clausilia, for instance, occurs in a list of shells drawn up by 

 von Martens (33) from East Russia, the Siberian plain, and the Altai 

 district, nor in a list (von Martens 35) of Central Asiatic Mollusca 

 from the mountain districts separating the South Siberian steppes and 

 the Aralo-Caspian deserts from the central highland of Mongolia, and 

 East Turkestan from the Pamirs and the neighbourhood of Lakes 

 Ala-kul and Issik-kul, up to a height of 11,000 feet. The same 

 author (von Martens 34), dealing with Central Asiatic Mollusca — the 

 district including Altai, Changai, Balchash, Issik-kul, Russian 

 Turkestan, Pamir Lakes, Yarkand, Kashgar, Ladak, Tarnur and 

 Chami, and Kukanor — remarks that so far Clausilia has not been 

 found there, nor are any recorded in his special memoir (von Martens 

 32) on the Mollusca of Turkestan. Gr. Nevill (42), recording the 

 results of the second Yarkand Mission, records no Clausilia from East 

 Turkestan and Ladak, nor from Kashmir, while Westerlund, dealing 

 with Siberian land and freshwater Mollusca, under the headings of 

 Siberia proper, east and west Baical region, Altai region, Amur 

 district, Kamschatka, includes no Clausilia in his list. Even in 

 a memoir on a district much nearer to Europe, Transcaspia, and 

 Khorassan, a district lying roughly from the eastern shore of the 



VOL. XI. — JUNE, 1915. 19 



