MARINK ALGAE FROM EASTER ISLAND 267 



The epidermal layer on the lower side of the thallus is also composed of 

 long rows of cells, but here the cells mostly remain undivided or they become 

 divided now and then by a longitudinal wall into two cells, and many of the 

 cells are not divided at all. The rows of rectangular cells, longer than broad, 

 are upon the whole much more distinct here than on the upper side. 



Fig. 14 a shows a radial transverse section of the thallus. The large cells 

 in the centre are about 60 (J. high and 80 ;x broad. On the upper side 3—4 

 or even more flat cells are cut of. The uppermost of these cells are divided 

 into smaller cells, forming the epidermal layer. From the lower side of the 

 large cells also 3—4 cells are cut off; the lowermost, especially the epidermal 

 ones, are again divided into smaller cells though fewer than in the epidermal 

 layer above. 



A tangential section of the thallus (Fig. 14 b) shows that the width of the 

 cells in each layer is only about half of that found in the radial section, and 

 the vertical walls are seen to be more or less distinctly undulated. 



From the epidermal cells below numerous rhizoids grow out having the 

 same moniliform appearance as those in the West Indian plant, and terminated 

 by a coralliform disc. Scattered hairs occur in small groups on the upper side. 



The specimens are sterile. 



Ralfsia ceylanica Harv., described and figured by Mrs. Gepp\ was later 

 regarded by Mrs. and Mr. GEPP 2 as a creeping form of Zonaria variegata. 

 After having seen the rather thick form from Easter Island, I feel inclined to 

 adopt this view. In an earlier paper 3 I referred it to Aglaozonia canarierisis 

 Sauvag , which is, in several respects, very similar. 



Area of distribution: Seems to occur in all warmer seas. 



Z. crenata J. Ag. 



J. Agardh, Till Algernes Systematik (Lunds Univers. Arsskr., T. IX, 1872, p. 48). 



■ ' A single large specimen is contained in the collection. As expressed by 

 J. AGARDH (1. c.) this species takes an intermediar position between Zonaria 

 flava and Z. Titrneriana, a view confirmed by the Easter Island specimen. 



The specimen was sterile. 



Area of distribution: West Australia, Malayan Archipelago etc. 



Fam. Fucaceae. 



Sargassum Ag. 



S. nov. spec, to be described by L. G. SjOSTEDT in a separate paper. 

 Very common, forming extensive associations in the lower litoral region. 

 Area of distribution: Endemic. 



1 Barton, E. S., List of Marine Algae collected at the Maldive and Laccadive Islands by 

 I. S. Gardiner (Journ. Linn. Soc, Bot., vol. 35). 



2 Marine Algae and Marine Phanerogams of the »Sealark» Expedition (Transactions ol 

 the Linnean Soc. of London, 2. Ser., Zool , vol. XII, part 4, 1909). 



' BorgeSen, F., Two crustaceous brown algae from the Danish West Indies (Nuova 

 Notarisia, Serie 23, 1912). 



