292 FRESH-WATER ALG^E OF THE UNITED STATES. 



found in considerable masses; can not be the same plant 

 observed here. 



Syn. Earlier authors classified these forms as Spermosira. 



Plate CXCVIII, figs. 3, 4, after specimens from Colorado 

 and from Pennsylvania. 



Genus 98, CYLIXDROSPERMUM, Kg. 



Thallus like that of Sphaerozyga, trichomes sheathless. Hetero- 

 cysts terminal, single ; spores originate in the cell next the 

 heterocyst. 



CYLINDROSPERMUM MACROSPERMUM, Kg. 



Trichomes curved or nearly straight, pale aeruginous, 

 more or less interwoven; joints globose or elliptic, often 

 mixed with others, somewhat cylindrical ; cell contents 

 usually somewhat granular. Heterocysts terminal, globose 

 or slightly oblong. Spores elliptic- oblong, or oblong cylin- 

 drical ; dark green or yellowish brown, or darker brown 

 when matured ; granular, twice as long as broad. 



Diameter of vegetative cells, 3-4 yw ; heterocysts somewhat 

 larger ; spores, about 14 yw. 



Syn. Andbcena inipalpebralis, Hass. ; Cyl. splitter ospermum, Eab. 



Plate CXC1X, figs. 6-8, normal appearance of the fila- 

 ments; fig. 14, Wood's figure. 



In ditches and on wet ground. 



CYLINDROSPERMUM LIMNICOLA, Kg. 



Filaments slightly curved, pale aeruginous, forming a 

 thin membranous thallus ; on garden and other soils in 

 damp, sultry weather ; very near the last, but slightly more 

 slender in filaments and spores. Probably merely a variety 

 of the same. 



Syn. Cyl. minutum. Wood. 



Plate CXCIX, fig. 11, cells often very close, with ends 

 compressed, presenting the appearance of Oscillaria; figs. 

 9, 10, after specimens from an almost dried up shallow 

 ditch ; many of the spores dropped off ; the filaments seem 

 to be true Oscillaria; fig. 12, Wood's figure of his Oyl. minutum. 



CYLINDROSPERMUM FLEXUOSUM, Eab. 



Stratum gelatinous, aeruginous, indefinitely expanded; 

 filaments equal, mostly flexuous and interwoven, often cir- 

 cinately or fasciately convulate ; sometimes straightish and 

 in bundles ; articles oblong, more or less contracted at the 



