1922] Setchell^Gardner : Phycological Contributions 379 



Growing on the pneiimatocysts of Nereocystis Luetkeana. IMoutli 

 of Tomales Bay, Marin County, California. Type, Gardner, no. 3456 

 (Herb. Univ. Calif., no. 207051), May. 



The structures designated zoosporangia( ?) in the above diagnosis 

 of this species were found interspersed among the gametangia. No 

 indication of the formation of zoospores has been observed, which leads 

 to the suspicion that they may be abortive gametangia. The terminal 

 cells of the erect filaments are often longer than the cells below it, and 

 in these filaments in which the cells are divided lengthwise, producing 

 the clavate condition, the terminal cell degenerates in a similar manner 

 as do the hairs in other species. The longitudinal division of cells in 

 the upper parts of the filaments is undoubtedly connected with the 

 formation of the short, lateral, often secund, gametangia characteristic 

 of nearly related species in Hecatonema and in Compsonema, for in a 

 few instances such gametangia were observed in old specimens in which 

 the gametes had. to a large degree, escaped from the characteristic 

 gametangia. 



Hecatonema Lawsonii sp. uov. 

 Plate 40, figures 5-7 



Frondibus pulvinulos microscopicos, 250-500;a diam., linea exteriore 

 irregulares formantibus; parte prostrata filamentis maxime contortis, 

 profuse ramosis, subterminaliter furcatis composita; filamentis erectis 

 stratum compactum valliforme filamenta pilifera numerosa sparsa 

 includens formantibus, 0.75-1.5 mm. longis; cellulis filamentorum 

 repentium radianter tangentialiterque divisis, in centro thalli pseudo- 

 parenchyma formantibus, forma irregularibus, 4-5ju, diam. ; cellulis 

 filamentorum piliferorum basi quadratis et vaginatis, superne usque 

 ad 25-plo longioribus quam latis; zoosporangiis ignotis; gametangiis 

 cylindricis usque ad leviter fusiformibus, 25-30;u, longis, 5-6. 5/^ latis; 

 loculis multis per parieties longitudinales et obliquos formatis. 



Growing on the sporophylls of Nereocystis Luetkeana. Uyak Bay, 

 Alaska. Type, Setchell and Lawson, no. 5131 (Herb. Univ. Calif., 

 no. 99357), August. 



Myrionema vulgar e Collins, Holden and Setchell, Phyc. Bor.-Amer. 

 (Exsicc), no. 924 (non Thuret). Myrionema strangulans Setchell and 

 Gardner, Alg. N. W. Amer., 1903, p. 249 (non Grev.). 



This plant superficially resembles very closely Myrionema foecun- 

 dum f. simplicissimum S. and G. Microscopic examination, however, 

 reveals several important differences. The creeping filaments are 

 unique. The branches are very numerous, come off at wide angles and 

 seem, for the most part at least, to be subterminal, or if the terminal 



