488 Vniversity of California PuMications in Botany [Vol. 8 



Setchell and Gardner, Mar. Al^. Gulf, of Calif., 1924, p. 724, pi. 17, 

 fig. 49. 



This organism is on the border between Myrionema and Comp- 

 sonema as Ave interpret these two genera (Setchell and Gardner, Phyc. 

 Cont. II-VI, 1922). Under the present condition of the host it is 

 impossible to learn much of the basal portion. It appears that the 

 basal layer was largely developed before the gametangia of the host 

 started to develop. Later the latter pushed out among the basal fila- 

 ments and leaving them behind developed along with the gametangia of 

 the epiphyte. The gametangia project beyond the general surface of 

 the host nearly their entire length. On account of the pluriseriate 

 nature of the gametangia, we have placed it in the genus Compsonema 

 rather than in Myrionema. 



8. Hecatonema Sauv. 



Fronds starting from a single cell, soon developing a series of 

 closely crowded filaments radiating in all directions, forming a com- 

 pact disk; the branching of radiating filaments often subterminal; 

 the cells of the radiating filaments wholly or in part dividing once hori- 

 zontally, thus creating a distromatic layer, the lower cells of which 

 may or may not produce short, penetrating, subulate rhizoids; the 

 upper layer of cells producing erect assimilating filaments, wholly 

 or in part producing gametangia, and hyaline hairs ; gametangia 

 pluriseriate. 



Sauvageau, Sur quelq. Myrionem., 1897, p. 248 (p. 88, Repr.). 



The type species of the genus is H. maculans, collected at Cher- 

 bourg, France, growing on Rhodymenia palmata Grev. The specific 

 name wa.s taken from Phycocelis maculans Collins (Bull. Tor. Bot. 

 Club., vol. 23, 1896, p. 459), the plants of which were distributed 

 in Collins, Holden and Setchell's Phycotheca Boreali-Americana 

 (Exsicc), no. 274. 



Key to the Species 



1. All of the erect filaments transformed into gametangia ...1. H. Lawsonii (p. 489) 



1. Part of the erect filaments transformed into gametangia 2 



2. Erect sterile filaments clavate 3. H. clavatum (p. 491) 



2. Erect sterile filaments cylindrical 2. H. variabile (p. 490) 



