OSCILLARIA. 317 



OSCILLARIA LITTORALIS, Carm. 



Stratum thin membranaceous, aeruginous, shortly radiat- 

 ing ; filaments rigid, endowed with active motion, vividly 

 oscillating ; articulations 4-5 to a diameter ; dissepiments 

 granular ; ends straight., broadly rounded ; light aernginons. 



Diameter of trichomes, 12-15 jj. 



Salt water marsh pools, New Jersey, Florida, and prob- 

 ably along the whole Atlantic Coast. 



Plate CO VII, figs. 18, 19, two parts of trichomes, from 

 New Jersey. 



OSCILLARIA PRINCEPS, Vanch. 



Stratum aernginons or dark blackish green, long rayed ; 

 trichomes straight or slightly curved, somewhat thinner 

 towards the ends, apices broadly rounded ; articulations 

 one-fourth to one-fifth as long as broad; cell contents steel- 

 blue. 



Diameter of filaments, 30-45 //. 



Syn. OstiUaria taenivides, Bory ; 0. aeruginea. Mart. 



Pools and ponds. 

 Plate CCVII, figs. 20-22, specimens of usual appearance. 



OSCILLARIA IMPERATOR, Wood. 



Occurring in an olive-black, mucous stratum, mostly 

 swimming ; with long rays ; trichomes straight or straight- 

 ish, light green or deep olive, tranquil, or oscillating slowly ; 

 moving with a gliding motion. Ends somewhat attenuate, 

 broadly -sub -truncate at the apices, slightly curved; 

 articulations 6-12 times shorter than the diameter, slightly 

 contracted at the joints; cytioplasm homogeneous, olive 

 green ; sometimes granular. 



Diameter of trichomes, normal form, 50-56 // ; smaller 

 forms, 38-45 //. 



The principal distinction between this species and the 

 preceding (princeps) is in the articulation which is very 

 variable; the former averages 4-5 ; the present 9 to diameter. 

 The diameter is more also. 



Frequent in ponds and pools from Maine to Florida. 



Plate CO VIII, figs. 3, 4, the typical form ; figs. 1, 2, a 

 smaller variety ; articulation, 6-10 times shorter than broad. 



