352 ART. 2. — H. MATSUMOTO: 



One specimen ; Okinawa, Riu-kin. 



Indo-Pacific. Okinawa may be the northern hmit of this 

 species. 



The Ophiuran Fauna of Japan. 



H. L. Claek distinguishes four geographical ophim^an faunae 

 in the North Pacific, namely Honshu, Bering, American and 

 Oceanic. I will discuss the ophiuran fauna of . Japan from a 

 somewhat different standpoint from his. 



All the known Japanese ophiurans are referable to eighty - 

 eight genera, which may be divided from the distributional stand- 

 point into five groups as follows. 



I. Cosmopolitan genera, which are widely distributed in both 

 the Indo-Pacific and Atlantic, as well as in both the 

 Arctic and Antarctic or either one of the latter. The 

 following genera belong here. 



Ophiacantha, Amphiactis, Amphiodia, AmphipJiolis, 

 Amphiura, Homalophiura, Ophiiira. 

 7 genera : ^%. 

 II. Arctic genera, which are essentially circumpolar in dis- 

 tribution or limited to the Bering Sea and very northern 

 Pacific. The following genera belong here. 



Gorgonocephalus, Ophiolehes, Ophiosemnotes, Ophiopho- 

 lis, Stegophiura, Ophiopenia. 

 6 genera : 1%. 

 HI. Intertropical genera, which are widely distributed in both 

 the Indo-Pacific and Atlantic, but not in the Arctic or 



Antarctic. The following genera belong here. 



Ophioleptoplax, Ophiomyxa, Ophiodera, Ophiohyrsa, 



