DJI V^ ti' izy ^ >^ j^ + H 

 THE BOTANICAL MAGAZINE. 



[Vol. V. June 10,1891. No. 53. ] 



A New Japanese Prasiola. 



Ryokichi Yatabe^ Sc. D. 



Prasiola japonica, nov. sp. 



Norn. jap. Kawa-iiori. H >^ ^ i; . 



ULVACEJE. 



(Plate XXV.) 

 Thallus expanded, delicately membi-anaceous, ovate, oblong, linear-oblong, 

 lanceolate, or irregularly lobed, crispate at the margin, bright green, 1-20 cm. 

 long, 0.5-4 cm. broad. Cells subquadrate, about///, in diameter, arranged 

 in fours. — Attached to rocks in clear rapid stream. 



In small specimens the thallus is miostly ovate or oblong, but in larger ones 

 often variously lobed and plicately crispate. It is attached to the surface of 

 rocks by a minute point. The surface view of the thallus under the micro- 

 scope shows that the cells are generally arranged in fours and about y jjl. in 

 diameter. Its margin is generally slightly undulate, but in some cases 

 irregularly notched. Its transverse section shows that it consists of one layer 

 of cells which are twice as long as broad. Towards the point of attachment of 

 the thallus the cells becomie elongated downwards into slender colorless fibres., 

 and at that point the thallus is attached by means of entangled fibres more or 

 less thickened at the lower ends. 



