Desmarestia tabacoides Okam. n. sp. 



Norn, Jap. : Tabako'gusa. 

 PL, XXXVIIL Fig. 1-4； PL. XXXIX, Fig. 9-13. 

 Tabacopsis acetosa Okam. 日 本 藻類 名觉 P. 121. 

 Dtagn. ： Fronds very large, leaf-like, shortly stipitate with broadly 

 oval, very usually obliquely lobed, simple, midribed and coriaceous 

 lamina. The midrib is slightly prominent below but gradually becoming 

 lainter upwards, with opposite veins which dissolve, even from the base, 

 into numerous fine veinlets. Sori forming irregularly rounaish patches 

 on both surfaces. Gametan^ia ovato-cylinarical or oblong, produced on 

 the apical portion of simple hairs being accompanied by sterile ones, 

 vJolour chestnut-brown when recent, soon changing into bluish-green when 

 exposed to air. 



Hab. : On rocks, stones or shells of Haliotis gigantia between tide- 

 marks. Nagasaki, Nemoto (Boshyii), Enoshima (Prov. Sagami), Onahama 

 (Prov. Iwaki). Gametangia : June-August. 



Dcscr. Fronds very large, leaf-like, rising from a circular disc with 

 a short subcylindrical stem which is 1-2 cm. long and about 2 mm. in 

 diameter. Lamina oval or oblong, simple and not lobed in young state, 

 being traversed by a slightly prominent midrib which becomes 

 weaker upwards and finally vanishes before reaching the apex. On 

 both sides of the midrib, there arise opposite veins which soon 

 dissolve, even from the base, into numerous fine veinlets and be- 

 come invisible to the naked eyes towards margins. The lamina is 

 very rarely almost simple and entire when old ； but it becomes usually 

 torn up obliquely into many lobes, whose indentation often reaches 

 the miarib. There is no regularity in the arrangements of these lobes 



