PH^EOPHYCE^E 101 



tion of the long branches the activity of the growing 

 point is mainly directed to the development of the 

 branches below the growing point, while during 

 the formation of the short ones, most of the cells 

 produced reinforce the growth in length of the 

 terminal shoot. 



The Reproductive Organs. Unilocular sporangia 

 are known in Desmarestia viridis, and are the 

 equivalents of superficial cells. In Arthrocladia 

 club-shaped chains of cells arising above the growing- 

 point of the short branches form the plurilocular 

 sporangia. Farther information is greatly needed on 

 the subject of the reproductive organs of this group, 

 and observations on the species of Dcsmarestia in 

 particular. 



The Geographical Distribution is mainly in the 

 north and south temperate seas. Arthrocladia villosa, 

 and Desmarestia mridis, D. aculeata, D. ligulata, D. 

 Dudresnayi are British, but most species of the 

 latter genus belong to the southern ocean. 



STRIARIACE.E. 



General Characters. The thallus, which attains 

 considerable length in many of the forms, is of 

 parenchymatous structure, and variously branched. 

 It grows in length at a meristematic region below 

 the apex. Both unilocular and plurilocular spor- 

 angia occur, developed as equivalents of superficial 

 cells or as outgrowths of such. 



The Thallus, which is rarely simple, but in most 



