HOW TO KNOW THE FRESH-WATER ALGAE 

 320b Cells cylindrical or crescent-shaped 321 



321a Cells elongate-cylindric, coiled or S-shaped, equally rounded at 

 both poles. See Fig. 219 OPHIOCYT1UM 



321b Cells oblong, sides convex, short-cylindric, or fusiform, sometimes 

 not equally rounded at both poles; curved but not coiled, nor 

 twisted 322 



322a Cells short-cylindric, 1V2-2 times as long as broad; poles sym- 

 metrically rounded. Fig. 227 MONALLANTUS 



^ rr ^^ •— ?v Fig- 227. Monallantus brevicylindrus 



y^W^W" • ° ®k Pascher. 



l$$^ : '^j&/ v 5 *-?! •-'' 7 ^his * s ^ e on ^y species reported from 



Y^^^'^pW nJ£ '-<? ^ e United States. It occurs in the same 



\-'-'.W^3r ^i±*S habitats with Ophiocytium (Fig. 219) and 



X^>^ Bumilleriopsis (Fig. 228). 



Figure 227 



322b Cells fusiform or cylindric only in part; poles unsymmetrical . . . 323 



323a Cells fusiform or sickle-shaped 



324 



323b Cells irregularly cylindrical; poles unsymmetrical. Fig. 228 



BUMILLERIOPSIS 



Fig. 228. Bumilleriopsis brevis Pascher. 



These cells have yellow-green chromatophores 

 and occur singly or in clusters which are definitely 

 colonial. The irregularly curved cylinders (rarely 

 somewhat fusiform) with the poles of the cells un- 

 like one another in shape, help in identification. 



Figure 228 



138 



