ANACYSTI8. 329 



ANACYSTIS PULVEREUS (Wood) Wolle. 



Cells very small, whitish-blue-green, irregularly subglo- 

 bose, oval or angular, associated in families. Thalli com- 

 posed of very numerous and densely crowded families, 

 irregular, sometimes confluent, mostly surrounded by a false 

 hyaline tegument ; aggregated into a bright glaucous, or 

 whitish-blue-green pulverulent stratum. 



Diameter of cells, 2-3 yw. 



Syn. Anacystis glauca, Wolle ; Pleurococcus pulvereus. Wood. 



Forms an extended stratum over the bottom of limestone 

 springs. The stratum is in places nearly an inch in thick- 

 ness, and when lifted by the hand is found to be loose and 

 crumbly. Found by Dr. Wood in Centre County. Found 

 in abundance also in Northampton and Lehigh Counties, 

 Pennsylvania, where limestone springs abound. 



Plate CCX, fig. 25, imperfectly represents a small part of 

 a stratum. 



ANACYSTIS MARGINATA, Kg. 



Families usually globular, sometimes flattened, often many 

 united, and flowing together, surrounded by a thin colorless 

 tegument. Cellules crowded, spherical, but sometimes by 

 mutual pressure, somewhat angular, light aeruginous. The 

 margins of the families colorless. 



Diameter of cellules, 3-4 ^ ; families, 80-300 yw. 

 Found in ponds of stagnant waters. 



Syn. Mycrocystis marginata, Kirch. 



ANACYSTIS BRUNNEA, ( Naeg. ) Wolle. 



Thallus gelatinous-membranaceous, light brown. Cells, 

 single or twin, crowded, tegument false, or diffused ; cytio- 

 plasm pale yellowish-brown, or greenish-brown ; finely gran- 

 ular. Cells very small, 1 /* diameter ; families 4-10 ^ ; often 

 much more in diameter up to 50-60 yu. 



The whole forming brownish olive floating masses in 

 stagnant waters. 



Syn. Palmella brunnea, A. Br. ; Aphanocapsa brunnea, Naeg. 



This form is not quite identical with Naegeli's descrip- 

 tion ; it is very near. I adopt the name to avoid a new term 

 for a very vague condition. 



Later observations show this form to be an old condition 

 of dathrocystte. 



