25 

 Delesseria radicosa sp. nov- 



t j« n ^ ^ ^ i) 



Diagnosis. Primary frond leafy, membranous, lanceolate, simple 

 or parted, shortly stipitate, serrate, with an obscure immersed midrib 

 and sub-opposite veins reaching marginal teeth, which grow up to 

 alternately branched, filiform, compressed, vein-less, secondary branches, 

 coalesced to each other and with other bodies by minute ciliary root 

 like processes, emitted from margin. Fruits 



Hah. and Loc. On the roots of Rytiplilea angusta mihi and 

 perhaps on rocks in sublitoral region. A few specimens are in my 

 possession, which were collected at Hakodate and Iwaki. They are at 

 present unknown more southward and along the coast of the Japan sea. 



Description. Primary frond leafy, thin membranous, lanceolate, 

 mostly furnished with a very short flattish stem, rising and expanding 

 from- branching underlying portion, traversed by an obscure immersed 

 midrib and subopposite veins which reach marginal teeth, simple or 

 parted, 1.5-2.5 cm long, 2.5-3.0 mm broad. Some of marginal teeth 

 and attenuated apex of frond elongate afterward into secondary com- 

 pressed filiform portion (0.5 mm broad) which ramifies alternately 

 and rather divaricately, and seems to have a tendency to expand here 

 and there into a leafy segment. Midrib is more or less well trace- 

 able in the primary frond, but not in the secondary portion whose 

 segments end in sharpish apices. Along the margin of filiform segments 

 and often at basal margin of the primary frond, minute ciliary processes 

 are set forth. They assist the serrature of margin, together with 

 marginal teeth, from which they are distinguished in construction. 

 Marginal teeth and filiform segments are terminated with a single 

 apical cell, while marginal ciliary processes have no apical cell, being 

 composed of bundles of elongated cylindrical cells. They are linear or 

 almost cylindrical (in surface view), arising from non-constricted base 

 and ending in roundish or expanded scutate apex. By means of those 

 root-like processes segments often coalesce together and the frond comes 

 to contact perhaps with other algre. 



Frond consists of 2 layers of cells ; the inner, of oblongo-angular, 

 larger, colorless, empty cells with thickish walls ; the cortical, of 

 angular flattish cellules. In surface view of frond under microscope 

 the midrib is not distinctly marked out, and the cortical cells covering 

 the median portion are not different in shape from the rest. 



