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 Antithamnion Plumula (Ellis) Thur. 



Nom. Jap. : Yotsn-f>asane. 

 PL. CLXXXIX. 



Antithamnion Plumula (Ellis) Thur. in Le Jolis List Alg. Cherb. 

 (1863) p. 112; Hauck Meeresalg. p. 71; Okam. Synopsis (2nd. edit.) 

 p. 95. De Toni Syll. Alg. IV, p. 1400. Conferva Plumula Ellis; Dillw, 

 Brit. Conf., 1809, t. L. Cullithamnion Ptimnila, refract itm, and poly- 

 acanthum Kiitz. Tab. Phyc. Xi, t. 83-84. 



Fronds fine, filiform (some ca. 150 ft thick in the midle portion), 

 deliquescently branched in dichotomo-pinnate manner, furnished beneath 

 the apex of every articulation with opposite or 4-verticillate, tetra- 

 stichously arranged " Kurztriebe." "Kurztrieb" on its inner that is 

 upper side carries laciniae arranged in a secund manner, and are almost 

 horizontal or refracted in older and lower ones, patent or widely parted 

 above ; laciniae simple or furnished with a few similarly arranged 

 divaricated lacinulae. " Kurztriebe " distichously arising on the frank of 

 rachis are decompound, while those alternating with them on the same 

 articulation are more simple or sparingly branched. Apices of all sorts 

 of branches are acute and sharp. Root fibres are transformed from 

 " Kurztriebe " arising from lower articulations of frond. Articulations 

 2-6 times long as diam., becoming shorter and subequal toward the apex 

 as well as the base of frond, cylindrical or slightly narrowed in the 

 middle. On the sides of upper articulations of young laciniae or 

 "Kurztriebe" gland-cells containing hyaline or yellowish mass are usually 

 seen. -Tetraspores globular or oval, mostly cruciate, situated solitary or a 

 few aggregated on the side of laciniae or lacinulae, mostly sessile, rarely 

 shortly pedicellated. Cystocarps large, globular, with 2-3 nuclei aggregated 



