MARINE AI.GAE FROM EASTER ISLAND 



2 93 



the basal part. Higher up they are longer and thinner. The uppermost joint 

 is 46 (j. broad only. 



The conceptacles are about 240 a broad. 



Area of distribution: Australia, Malay Archipelago, Easter Island. Also 

 Mediterranean? 



Fam. Ceramiaceae. 

 Ptilothamnion Thur. 



P. Pluma (Dillw.) Thur. -- Fig. 34. 



Thuret, G., in Le Joi.is, Liste Alg. Cherb., p. 118. Bornet et Thurkt, Notes 

 algologiques, p. XII et 179, pi. 46. — Conferva Pluma Dillw., Intr. n. 119, tab. F. 

 — Callithamnion Pluma Ag., Spec. II, p. 162. Harvey, Man., p. 115; Phycol. Brit., 

 pi. 296. Hauck, Meeresalgen, p. 75, fig. 27. 



Growing upon a stone among several other algae some small specimens 

 were found which I have referred to P. Pitt ma. A safe determination is hardly 

 possible, the material being ste- 

 rile with the exception of a few 

 tetrasporangia. Should the de- 

 termination prove correct, the 

 occurrence of a species hitherto 

 known only from the Mediter- 

 ranean Sea and adjacent parts 

 of the Atlantic, in the Pacific 

 Ocean, is very remarkable. 



Below I want to give a 

 short description and some 

 figures of the plant to show 

 how well it accords with the 

 descriptions of P. Pluma, f. i. 

 with that of Hauck, 1. c. 



The horizontal creeping 

 and ramified filaments (Fig. 34 a) 

 are fixed to the substratum by 

 means of vigorous rhizoids 

 ending in a broad disc and 

 composed of cylindrical cells 

 about 16 \l broad and as much 

 as 70 [j. long. The erect fila- 

 ments (Fig. 34 b) are unbranched 

 below; thence every cell car- 

 ries two opposite branchlets, all 

 lying in the same plane. The 



branchlets are directed upwards, Fig. 34. Ptilothamnion Pluma (Dillw.) Thur. a part of 



, , c 1 . „^o creeping filament with rhizoid and erect branches, c. !8 % ; 



under an angle of about 30. b er p ect " shoot> c . i» /i; c part of thallus with tetraspo- 



They are composed of mostly rangia, c. 240 /i. 



