B> o s t e I s t a 187 



actinotrichia, Brachycladia australis, 

 Hydroclathrus cancellatus, several species 

 of Laurencia, Sukria japonica, Cysto- 

 phyllum fiisiforme and many other 

 beautiful plants are found in this vicin- 

 ity. Nearly a dozen species of Sar- 

 gassum are to be looked for here. In- 

 stead of the Laminarias and AlaHas, 

 so characteristic of the northern coast, 

 one now finds Ecklonia {E. cava and 

 E. bicycles), which, together with Sar- 

 gassum, cover densely the sublittoral 

 rocks. Only one Laminaria (L. radi- 

 cosd) can be collected in this district. 

 The chain of volcanic islands which 

 connects Bonin island with the Province 

 of Izu enjoys a warmer climate, and 

 the marine flora is somewhat tropical, 

 that of the southern end of Bonin 

 island being altogether so. The current 

 washing some of these islands influ- 

 ences also the entrance of Tokyo bay 



