40 



Hab. : On rocks extending from high tide to below low-water 

 mark. Okinawa Isl. and Raleigh rock (Ryukyu); Prov. Satsuma ; 

 Nomo and Hirado (Prov. Hizen); Provs. Bungo, Tosa, and lyo ; 

 Owase (Prov. Kii) ; Provs. Shima, Mikawa, Idzu, Sagami, Awa, 

 Hitachi, Iwaki and Rikuzen ; Miyako (Prov. Rikuchyu), Hakodate ; 

 Provs. Iwami, Tango, Wakasa, Noto, Yechigo, Sado and Uzen ; 

 Hebiura and Oma (Prov. Mutsu), Riishiri (Hokkaido). Fruits :-late 

 spring to summer. 



Remarks. Size of frond, habit and breadth of branches, mode of 

 ramification, characters of terminal segments etc. much vary according 

 to specimens from different localities. But as it is difficult to separate 

 one from another as a distinct species, there being several gradations 

 from one form to another, I think all those variations as the dif- 

 ferences of forms, consideriug that many diffterent species illustrated 

 in Kuetz. Tab. Phyc. /. c. are put under one species as the forms 

 of Dictyota dicJiototna. 



Those forms which I took for the typical one have more or 

 less flabellately expanded regularly dichotomous frond, having 

 mostly erect, entire and flat (/. e. not torted) segments, ending in 

 blunt and einarginate apices with the breadth of segments varying 

 from 2 to 10 mm. (mostly 5-6) and 10-15 cm. in height (PI. CXI, 

 fig. 1-3). From those forms there are some deviations among the 

 typical ones in torting of segments, spreading of parts and taper- 

 ing of apices (PI. CXII, fig. 2-3). In some specimens proliferations 

 are produced both from margins and surfaces (PL CXII, fig. i, 7). 

 In robust ones fronds often attain the height of 30 cm. and 

 epidermal cells are here and there (mostly at margins) seen to be 

 transversely divided into two. They are thicker in substance and 

 have darker brownish colour than usual forms which have thin 

 membranaceous substance and light yellowish-brown colour. Those 

 robust forms let us remind our Pachydiclyon coriaceum which how- 



