F. Børgesen: List of species. 



463 



part of the filaments (Fig. 423 a). The rhizoids are unicellular, 

 having in their basal end a flat roundish, coralhform disc. The 

 rhizoids are given off mostly in the basal proximal ends of the 

 cells near the cross walls (Fig. 423 a), but now and then, too, a 

 rhizoid (mostly smaller) is issued in the upper (distal) end of the 

 adjacent cell. 



The ramification is not very abundant; being mostly re- 

 stricted to a few branches in the older parts of the thallus, 

 the upper ends of the filaments often being undivided. As pointed 

 out by Asken AS Y a pecuharity is to be noted regarding the issue 

 of the branches, these not being given off at the distal end of 

 the cells, as is ordinarily the case in related forms, but near the 

 basal wall of the cells (Fig. 423 a). 



The cells are nearly cylindrical or a little thicker at both 

 ends; about 200 ju thick and 4 — 6 times as long. The wall is thick 

 in the older parts of the thallus. Near the apex of the filaments 

 the young cells become gradually shorter and a little swollen at 

 their upper end. 



Round the upper end of the young cells is early formed a 

 dense ring composed 

 of several rows of hairs. 

 These are di-trichoto- 

 mously ramified and 

 are soon shed, long 

 before the cell has 

 reached its normal size. 



The tetrasporan- 

 gia (Fig. 423 b) are 

 formed upon shorter 

 or longer, pyriform to 

 clavate, unicellular pe- 

 dicels, one upon each 

 of these. They form a 

 dense ring at the upper 

 ends of the cells, a 

 little above that of 

 the hairs or scars of 



these. Asken ASY found Fig- 423. Criffithsia tenuis Ag a basal part of 



a plant, b, apex of filament with tetrasporangia. 

 about ten only in each (a about 17:1 b, about 85:1). 



