Hedophyllum spirale, sp. nov., and its relation 

 to Thalassiophyllnm and Arthrothamnus. 



By 

 K. Yendo, RigalmsM. 



With Plate VL 



Hedophyllum spirale, sp. nov. 



Frons junior lamina siniplici abovato-cimeata, stipite brevi subcylindraceo 

 solicio ; aclultior marginibus laminae exterioribiis crassissimis ad basin, intus 

 spiraliter involutis, stipite crassiore subcompresso brevissimo solido ramosissimo. 

 Pars media laminae sensim extra et deorsum ad usque ad basin, sinum 

 inter duo volumines relirjquens, obliteratur ; volumen laminam in plures 

 lacinias longitudinaliter fissam emittens. Medulla, in sectione transversali 

 stipitis ellipsoidea. Sori in maculas basi laminae ambitibus irregularibus. 



Habit, ad insulam Shimushu. 



f. kamtschatkensis, f. nov. 



Frons major, stipite 20-30 cm longo, basi subtereti, sursum compresso 

 expanso marginibus involutis. 



Habit, ad pras Yavinam, Kamtscbatkae. 



During the three months stay at Shimushu, the island at the northern 

 extremity of the Kurile Isles, I could satisfactorily study the marine vegeta- 

 tion in its vicinity. The present species is one of the common Lamina- 

 reaceoics algae found covering the extensive reefs in front of Kataoka Bay, 

 at low tide hours. 



The earliest stage of the plant begins to appear late in July or at 

 the beginning of August. The lamina is oblong obovate with a short and 

 subcylindrical stem. The mucilage canals are found in lamina traversing 

 beneath the both epidermal layers. In the stipe as well as the ramuli of 

 the holdfast there are glandular cavities^^ in the form of ring close by the 

 peripheral margin (fig. 5). 



When the plant has grown about 7-10 inches long, the lamina expands 



1. In the cross sections of a stem, these cavities have similar appearance to the primary 

 stage of the mucilage ducts. But they do not develope further, remaining as elliptical 

 cavities elongated tangentially. Hence it would be advisable to treat them under different 

 name to avoid the confusion with the true mucilage canals. 



