CHAP, xxii.] MOLLUSCA. 521 



Japan, the other half in Moluccas, New Guinea, and Australia ; 

 Cyclotopsis (2 sp.), India and Malaya : Eegistoma (9 sp.), Philip- 

 pines and Moluccas, New Caledonia and Pacific. 



Characteristic of the Neotropical region are : Cyclotus (111 

 sp.), half in the Antilles and Tropical America, the rest in the 

 Moluccas, China, Malaya, India^ Natal, and the Seychelle 

 Islands; Megalomastoma (27 sp.), abundant in Cuba, West 

 Indies, and South America, others in India, Malaya, and 

 Mauritius ; Jamaica (2 sp.), Jamaica ; Licina (5 sp.), Antilles ; 

 Chodnopoma (49 sp.), Antilles; Ctenopoma (25 sp.), Antilles; 

 Diplopoma (1 sp.), Cuba; Adamsiella (15 sp.), Jamaica, Cuba, 

 Guatemala ; Cyclostomus (113 sp.), abundant in Antilles, also 

 occurs in Madagascar, Arabia, Syria, Hungary, and New Zealand ; 

 Tudora (34 sp.), Antilles, and one species in Algeria ; Cistula 

 (40 sp.), Ghondropoma (94 sp.)> Bourcieria (2 sp.), Tropical 

 America. 



Peculiar to or characteristic of the Palsearctic region are : 

 Craspedopoma (5 sp.), confined to Madeira, the Azores, and 

 Canaries ; Leonia (1 sp.), Spain and Algeria ; Pomatias (22 sp.), 

 Europe and Canaries with a species in the Himalayas ; Cecina 

 (1 sp.), Manchuria. 



The Ethiopian region has the peculiar genus Lithodion (5 sp.), 

 Madagascar, Socotra, and Arabia; and Otopoma(l$ sp.), Mascarene 

 Islands and Socotra, with a species in Western India and another 

 in New Ireland. 



The Australian region is characterised by Gallia (3 sp.), in 

 Ceram, Australia, and the Philippines respectively ; Realia (7 

 sp.), New Zealand and the Marquesas Islands ; OmpJialotropis 

 (38 sp.), the Australian region, with some species in India, 

 Malaya, and the Mauritius. 



The remaining genus, Hydrocena (27 sp.), has a very 

 widely scattered distribution, being found in South Europe, 

 Japan, the Cape, China, Malaya, New Zealand, the Pacific 

 Islands, and Chili. From 10 to 20 per cent, of new species have 

 been since described in most of the genera of this family. 



