1925] Setchell-Gardncr: Melanophyceae 391 



filament from a more or less conspicuous apical cell ; older cell walls 

 becoming dark colored when treated with eau de javellf ; chromato- 

 phores numerous in each cell, usually disk-shaped; zoosporangia uni- 

 locular, large; gametangia plurilocular, similar or with some distinc- 

 tion as 1() size and miiiilicr of loeuli (mega- and meio-gametangia) ; 

 zoosporangia and gametangia borne on separate (macroscopic) plants 

 differing little, if at all, in size or complexity and formed from the 

 transformed apical portions of usually short branchlets; propagula 

 present and characteristic in certain species of Sphacelaria, arising 

 from the transformation of lateral branchlets, producing a short 

 stalked body with longer or shorter radiate terminal branches, the 

 whole separating from the branch bearing it and developing into a 

 new plant. 



Spliacelariales Oltmanns, Morph. und Biol, der Algen, vol. 2, 1922, 

 p. 83. Sphacelariaceae Reinke, Ber. d. deut. bot. Gesell.. vol. 8, 1890, 

 p. 203. 



The ISphacelariales form a natural group, coordinate but distinct 

 from the Ectocarpales in that all the species included take their growth 

 from a conspicuous and very characteristic apical cell. The species 

 are, also, more or less polysiphonous through longitudinal division 

 walls, producing fronds unlike those of any of the species we have 

 included under Ectocarpales. The cell wall is 'said to differ in composi- 

 tion, or constitution, from that of any of the species of Ectocarpales, in 

 that, when older, it darkens when treated with eau de javelle, turning 

 black in mature cells. The members of the Sphacelariales resemble 

 those of the Ectocarpales in having unilocular zoosporangia and pluri- 

 locular gametangia on macroscopic plants closely resembling one 

 another in size and structure. In some species the gametangia are 

 differentiated into two types, megagametangia or oogonia with few and 

 large loeuli, and antheridia with numerous and small loeuli. Oltmanns 

 (loc. cit., p. 85) divides the order into three families; Sphacelariaceae, 

 Cladostephaceae, and Stypocaulonaceae, of which only the first, so far 

 as we know, is represented on the west coast of North America. 



FAMILY 1. SPHACELARIACEAE REINKE, emend, oltmanns 



Thallus of erect filaments from a discoid or thalloid base, mono- 

 siphonous at the tip or throughout, polysiphonous and. at tinu's, cor- 

 ticated below ; apical cell short, but conspicuous, not giving rise 

 directly to the initials of the branches, but these arising from the 

 apical portion of a cell already segmented, and usually situated at 



