274 FRESH-WATER ALGJE OF THE UNITED STATES. 



branches short, variously curved, somewhat rigid, mostly 

 ascending ; cells in simple or double or triple series ; sheath 

 thick, firm ; in the mature filament deep reddish brown, in 

 the branches yellow-brown, at the apices of the branches 

 nearly colorless and transparent. 



Moist clay banks, moist rocks, and the like. Habitat dis- 



t/ / 



tinct from the last, 8. Ugnicola, but otherwise, could not be 

 separated ; it is like it very polymorphic. 



Plate CXCIII, figs. 12, 13, two of the simplest forms from 

 a cluster ; figs. 1, 2, are as characteristic of the plant. 



SIROSIPHON BRANDEGEEI, Wolle. 



A form of which no full description can be given, as the 

 only specimen received was very limited. It was collected 

 by T. S. Brandegee, on the shores of a soda spring, Colorado. 

 Filaments short with apices subacute, reddish brown; cells 

 one, two, or three seriate. Microgoiiidia-bearing cells en- 

 large to form sporangia; these eject macrogonidia which de- 

 velop into Gloeocapsa or CAroococews-forms, mostly simple, 

 having but one nucleus which gives rise to a young plant. 



Diameter of filaments, about 20 ^ ; younger forms, 12-15 yw. 

 Soda Springs, Cannon City, Col. 



Plate CXCIV, figs. 17-20, older and younger forms ; figs. 

 21-23, intermediate forms of development, of the character 

 of Microcystis and Cliroococcus cells ; figs. 24-27, various con- 

 ditions of young, developing forms. 



SIROSIPHON CRTJSTACEUS, (Ag. ) Eab. 



Stratum thin, sub-tornentose, fuscous-black ; trichom.es 

 decumbent, densely intricate, branches longer or shorter, 

 sometimes inclining to corymbose near the ends, erect 

 flexuous, subtorulose, apices rounded or subacute ; cells in 

 simple series, rarely two series, globose, loosely disposed, 

 light aeruginous ; sheath rather ample, colorless, hyaline, 

 more rarely light yellow. 



Diameter of filaments, 15-18 yw. 



Syn. Scytonema crustaceum, Ag. ; Scy. velutinum, Wallr. ; Sirosi- 

 phon velutlnus, Kg. ; Sirosiphon rhizodes, Breb. 



Moist rocks, Charlotte, Vt. 



Had this plant from only one locality. It is very near to 

 S. rhizodes, but larger ; S. crustaceus is so nearly the same, 

 they are probably varieties of the same species. 



