CHAP. XXII.] 
MOLLUSC A. 
521 
Japan, the other half in Moluccas, New Guinea and Australia ; 
Cyclotopsis (2 sp.), India and Malaya : Registoma (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; Jamaicia (2 sp.), Jamaica; Licina (5 sp.), Antilles; 
Choanoporna (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.), Chondropoma (94 sp.), Bourcieria (2 sp.), Tropical 
America. 
Peculiar to or characteristic of the Palse arctic region are : — 
Craspedopoma (5 sp.), confined to Madeira, the Azores and 
Canaries ; Leonia (1 sp.), Spain and Algeria ; Pomaticis (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 (19 sp.), Mascarene 
Islands and Socotra, with a species in Western India and another 
in New Ireland. 
The Australian region is characterised by Callia (3 sp.), in 
Ceram, Australia, and the Philippines respectively ; Realia (7 
sp.), New Zealand and the Marquesas Islands; Omphalotropis 
(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. Erom 10 to 20 per cent, of new species have 
been since described in most of the genera of this family. 
