F. Borgesen: Rhodophyceæ of the Danish W. Indies. 



405 



Towards the surface these cells are covered by a cortical 

 layer, this consists of oval — roundish cells forming a more or 

 less dense cover. Above the cross-walls of the cells, where these, 



Fig. 390. Coelarthrum Albertisii (Piccone) Borgs. 



A, transverse section of a joint at the apex of the thallus (about 10:1); 



B, C, transverse sections of the wall, B with a gland, C with tetraspores 

 (70:1); D, large cells of the wall seen from the inner side (70:1); E, do. 

 with glands (150:1); F, the wall seen from the surface showing also the 

 underlying cells (150:1); G, part of the cortical layer with tetraspores (150 :1). 



because of their roundish shape, leave some space open, some 

 larger cells are found (Fig. 390 F) and from these larger cells 

 smaller ones are given off growing out over the surface of the 

 large wall-cells. 



The diaphragms consist of a single or two layers of cells ac- 



