76 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



cation of the main branches, is kept distinct by most writers. "We have but a very 

 imperfect representation of the Sphacelarioid group in this country. Stypocaulon and 

 Halopteris are entirely wanting, and of Sphacelaria we have only S. eirrhosa and S. 

 radicans on the northeastern coast, S. tribuloides in Florida, and what is supposed to 

 be S. fusca in California. The species of Sphacelaria are variable, and the determina- 

 tion sometimes uncertain. The apical cells of our Sphacelaria} are frequently attacked 

 by the unicellular parasite, Chytridium sphacelarum, Kny. 



S. cirrhosa, (Roth) Ag. ; Phyc. Brit., PL 178. 



Fronds olive-brown, densely tufted half an inch to two inches high ; 

 main filaments erect, several times pinnate with opposite or irregularly 

 spreading branches; rhizoidal filaments few or wanting; unilocular 

 sporangia .08-7 mm long, globose ; plurilocular sporangia .05 mm broad by 

 ,08 mm long, broadly ellipsoidal, secund on lateral branches, with unicellu- 

 lar pedicels; propagula rather stout, three (2-4) rayed, usually borne 

 on distinct plants. 



Common on Fucus, on which it forms dense globose tufts. Europe. 



A variable species, sometimes with regularly opposite branches, at times with 

 irregularly placed long branches. The propagula vary very much in size, and are 

 generally found ou plants which do not bear sporangia. With us they are much more 

 common than the sporangia. An excellent account of the propagula is given by 

 Janczewski in the Annales des Sciences, Series 5, Vol. XVII. In the Nereis Am. Bor. 

 the word propagulum is used by Harvey to signify the contents of the apical cells, and 

 this use of the word should not be confounded with its present application. The word 

 propagulum as used in the Nereis is rather equivalent to the term sphacela of other 

 writers. Sporangia are more common in the winter months, but are found occasion- 

 ally in summer. 



S. radicans, (Dillw.) Harv. (#. olivacea, var., Ag.; Pringsheim, 1. c, 

 Pis. 9 and 10.— 8. radicans, Phyc. Brit., PI. 189.) 



Fronds olive-brown, half an inch to an inch high, forming dense turfs ; 

 filaments erect or prostrate, branches few, somewhat appressed, rhi- 

 zoidal filaments often numerous ; unilocular sporangia globose, .04-5 mm 

 in diameter, numerous on the branches, on very short unicellular pedi- 

 cels; plurilocular sporangia unknown; propagula slender, elongated. 



On mud-covered rocks between tide-marks. 



Newport, B. I. ; Wood's Holl, Mass., and common from Nahant north- 

 wards; Europe. 



The present species is smaller than the last, and forms small, indefinitely expanded 

 curfs, especially on the under side of mud-covered rocks, often in company with Cera- 

 tiium Hooperi. Numerous rhizoidal filaments are sometimes found at the base, so that 

 rtiiferent plants are bound together, but the species is without a false cortex. The 

 name originally proposed for the species by Dillwyn was S. radicans. Agardh adopts 

 Dillwyn's later name, S. olivacea, making of the form with numerous rhizoidal fila- 

 ments a variety, radicans. Apart from their different habit and place of growth, it is 

 difficult to assign exact marks by which to distinguish in all cases S. cirrhosa and S. 

 radicans. In the latter the secondary branches are few and appressed, irregularly 

 placed, never opposite, while in the former they are numerous, given off at wide 



