Peyssonnelia involvens Zanard. 



Morn. Jap. : Kuda-iwanokcaaa. 

 PL. LVII, Fig. 11-17. 



j\-yssonnclia ini'ohcns Zanard. Plant. Mar. Ruhr. p. 269, tab. IX, 

 f. 2 ; De Tcni Syl!. Alg. IV, p. 1/03. 



Frond crustaceous, thin and soft leathery, with one or rarely 

 two-celled root-fibres, thickly incrustated beneath the cells forming the 

 basal decumbent layer and is tubular by the union of the both edges 

 covering round the substratum on which the plant lies. 



Hab : Cast up ashore (probably on rocks near high tide a little 

 below high-tide). Koshun (Taiwan) col. by K. Miyake. Sorns : 

 January (Taiwan). 



Ramarks : Only one specimen before us. The frond is sub-cy- 

 lindrical and tubular taking irregularly dichotomo-decompound sub- 

 flabellate shape, but we can not conceive that the plant comes out 

 always in the same appearance. We would suppose that the tubular 

 form is the result of the decay or disappearance of some dichotomous 

 frond on which the plant grew. 



PL. LVII, Fig. 11-17. F'g- 11: i'rond of Pcvssonnclia invohcns 

 Zanard. \. Fig. 12 : portion of the frond, \. Fig. 13 : cross-section 

 of a branch, decalcified ; a, place where two edges of the frond have 

 united., 5 1 4 . Fig. 14: portion marked a in Fig. 13, magnified; the 

 whole thickness of the lower wall of the cells forming the basal 

 decumbent layer becomes visible after decalcilkatiun, 3 '^. Fig. 15 : 



