OSCILLAR1A. 311 



OSCILLARIA CHLORINA, Kg. 



Sometimes swimming on the water as a dirty greenish 

 stratum, sometimes diffused in the water ; filaments straight, 

 actively moving, either articulated and having the cytio- 

 plasm filled with blackish granules, or else neither articu- 

 late nor granulate ; cytioplasm hyaline, almost colorless, or 

 with a faint greenish tint 5 ends of filaments straight, ob- 

 tusely rounded ; joints about equal to the diameter. 



Diameter of filaments, about o /^. 



Collected by Dr. H. C. Wood, on brick-ponds, near Phila- 

 delphia. 



OlSCILLARIA GRACILLIMA, Kg. 



Trichomes straight, curved and sometimes coiled, solitary, 

 or forming a thin membranaceous stratum. Threads ob- 

 tusely rounded at the apex, often bent. Cell Contents light 

 aeruginous, articulations not always distinct, about as long 

 as wide. 



Diameter of filaments, 2.7-3.2 //. 



Plate CCVI, fig. 6, from specimen floating on pond. 



OSCILLARIA LEPTOTRICHA, Kg. 



Trichomes scattered, or collected in a very thin blue green 

 stratum, slender, slightly curved, indistinctly articulate, 

 joints twice as long as wide, or after division equal; very 

 minutely punctate at the periphery ; attenuated at the ends, 

 which are straight, curved or defiexed ; cell contents pale 

 blue, or green. 



Diameter of threads, 3 yw. 



Plate CCVI, fig. 7, filaments collected in ditches of brack- 

 ish water, New Jersey. Prevails in fresh-water also. 



C. Articulation one-half as long as wide. 



OSCILLARIA VIOLACEA, Wallr. 



Filaments long, straight, radiating, forming a gray-violet 

 membranaceous stratum, ends of filament somewhat reduced, 

 and often drawn out to a thin point; articulations 2-j. to 

 diameter, which is, 4-4.7 /*. 



Most frequent in green-houses. 



Plate CCVI, fig. 10. 



OSCILLARIA AERUGINEO COERULEA, Kg. 



Forming a submembranaceous, mucous stratum, bright 

 blue-green ; filaments long, nearly straight, radiating, oscil- 



