310 FRESH- WATER ALG;E OF THE UNITED STATES. 



OSCILLARIA DETERS A, Stiz. 



Forming reddish olive, diffused strata ; trichomes rather 

 rigid, densely intricate, oscillating freely ; slightly curved, 

 rule-scent ; articulation distinct or indistinct, equal to one- 

 half longer than the diameter ; apices somewhat bent, obtuse. 



Diameter, 2 jn. 



Stagnant waters, Rochester, New York. 



OSCILLARIA AMPHIBIA, Ag. 



Filaments straight, forming a membranous stratum, light 

 green, apices obtuse, straight, vibrating actively, articula- 

 tion equal or subequal ; cell contents light blue-green. 



Diameter of trichomes, 1.8-2.8 //. 



Coating wood subject to hot waste water from steam 

 engines. 



Plate CCV, fig. 3, from hot water, temperature of about 

 110 Fahrenheit. 



B. Articulations about as long as wide. 



OSCILLARIA ELEGANS, Ag. 



Filaments slender, straight or slightly curved, forming a 

 dense floating stratum ; threads radiating, bright aeruginons 

 green, or with age somewhat olivaceous ; apices attenuated, 

 curved. Articulations about equal in length and breadth ; 

 cell contents light aeruginous. finely granular or homo- 

 geneous. 



Diameter of filaments, 2. 8-3 j^ ; rarely 3. 5 //. 



Plate CCVI, fig. 4, from specimens floating on spring 

 water ; also attached to water grasses. 



OSCILLARIA ANTLIARIA, Juerg. 



Thallus gelatinous, broad, submembranaceous, dark steel 

 blue or turning to olivaceous ; filaments rather rigid, 

 straight, often tranquil, sometimes oscillating, curved at the 

 attenuated apex, articulations indistinct, about as long as 

 wide; cell contents pale steel blue; nearly homogeneous. 



Diameter of filaments, 4.5-5.5 yw. 



Syn. Oscillaria parietiua, Vauch. ; 0. autumnalis, Kg. 



Around pumps, cisterns, etc. 

 Plate CCVI, fig. 8, rather frequent. 



