624 CLARK: DISTRIBUTION OF ECHINODERMS 



3. Caribbean Sea and the western coast of Central America: 

 Hemipholis, Ophiocryptus, Ophiozona. 



4. Caribbean Sea and the Galapagos Islands (probably in 

 reality the same as the preceding) : Sigsbeia. 



5. Peru to southern California (some only in part): Astro- 

 caneum, Diopederma, Gymnophiura, Platasterias, Nidorellia, Am- 

 phiaster, Paulia (Galapagos Islands also), Pharia, Phataria, 

 GaenocentroUis (Galapagos Islands also), Tetrapygus. 



6. Caribbean Sea and eastern Atlantic, the Hawaiian Islands, 

 southern Japan and the Kei Islands: Caenopedina. 



7. Western coast of Mexico, the Hawaiian Islands, Australia, 

 Tasmania, Lord Howe Island, the Mediterranean Sea and the 

 adjacent parts of the Atlantic: Centrostephanus. 



8. Southern and Lower California, southern Japan and south- 

 ern Australia : Heliocidaris. 



9. Caribbean Sea and the Hawaiian Islands: Podocidaris. 



10. Caribbean Sea and southern Australia: Ophioprium. 



11. Southern California and New Zealand: Ophiopteris. 



In view of the past intercommunication between the Carib- 

 bean Sea and the Pacific the similarity of certain elements of 

 the Caribbean fauna and of that of the western coast of tropical 

 America is not surprising; the latter, however, includes a very 

 considerable number of genera which occur nowhere else, to- 

 gether with a few species of characteristic Indo-Malayan types, 

 such as Mithrodia, Acanthaster, Anthenea, Leiaster, Astropyga, etc., 

 which are not represented in the Caribbean Sea. 



A significantly large number of genera, including well-known 

 and conspicuous littoral types, inhabit a more or less extensive 

 portion of the following anomalous range: Mediterranean Sea, 

 Caribbean Sea, southern Australia and New Zealand, southern 

 Japan, the Hawaiian Islands, and the western coast of tropical 

 America. 



This discontinuous range, though indicated by very diverse 

 types and only in part by each, nevertheless must be considered 

 a zoogeographic unit. Its outstanding feature is the fact that it 

 represents the extreme outer limits of a tropical and subtropical 

 faunal region the center of which is the Indo-Malayan region. 



