SHALLOW-WATER STARFISHES 349 



Peru, nor on the Atlantic coasts of America. Yet a much more 

 closely allied species, P. pectinifera (Miiller and Troschel), is found 

 on the coasts of Japan, extending north at least as far as Vladivostok. 

 Thus, the North American species is most likely a derivative of the 

 Japanese stock. The restricted genus, itself, is widely distributed in 

 the Indian and Pacific oceans, from Cape Good Hope to Australia 

 and Japan, but the Japanese species referred to is decidedly nearer to 

 P. miniata than any of the others. 1 All the species of the genus are 

 littoral and shallow-water forms. This renders their wide distribu- 

 tion more remarkable. Poraniopsis inflata Fisher is allied to P. 

 echinaster Perrier, of Patagonia, etc. Odontaster crassus seems to be 

 related to the several forms of the same genus found off Patagonia 

 and Cape Horn, but perhaps no more so than to the three species 

 found off the Atlantic coast of the United States, especially O. 

 robustus Verrill and O. hispidus Verrill. Ceramaster patagonicus is 

 thought by Professor Fisher to have a continuous range, in the deep 

 sea, from Patagonia to Alaska and Japan. The same, he thinks, may 

 be true of Ctenodiscus crispatus. I have not personally studied Ant- 

 arctic specimens of these species. Luidiaster dawsoni belongs to a 

 deep-sea genus, widely distributed. 



The preceding brief analysis of the fauna! lists indicates pretty 

 clearly that much the larger part of the starfishes inhabiting shallow 

 waters of the North Pacific coast, from middle California to Southern 

 Alaska, originated on that coast and have received, at most, only a 

 few additions from the Arctic Ocean and from the Panamic and 

 South American faunae, in modern (geologic) times. 



About one-half (forty-nine) of the total number of species and 

 varieties in the lists belong to the family Asteriidae. 



VII. RELATIONS OF THE SOUTH CALIFORNIAN FAUNA. 

 The list above includes twenty-nine species and varieties. Of these, 

 twenty-two species occur farther north. Of the remaining six species, 

 three are known to occur in the Panamic fauna, and probably find 

 here their northern limits, viz., Marthasterias sertulifera; Echinaster 

 tenuispinus; Linckia Columbia. These belong to genera widely dis- 

 tributed in tropical seas. The remaining three, at present, seem to 

 belong particularly to this fauna, viz., Astropecten siderealis; A. 

 ornatissimus ; Orthasterias gonolena. 



1 Professor Fisher, op. cit. iQiifr, p. 258, has given a rery useful table of their 

 differences. 



