Myxophyceae 35 



83. Microcystis flos-aquae (Wittrock) Kirchner in Engler and Prantl. Nat. 



Pflanz. I I a. 56. f. 49 N. 1900. De Toni. Syll. Algar. 5: 86. 1907. 



Tilden. Notes on a Collection of Algae from Guatemala. Proc. Biol. 

 Soc. Wash. 21: 153. 1908. 



Plate II. fig. 18. 



Colonies more or less spherical or oblong, with an indistinctly limited 

 tegument, often several lying close together, pale or yellowish blue-green; 

 cells 4-6.5 mic. in diameter, spherical, often densely crowded; cell contents 

 showing vacuoles, pale bluish-green. 



• Central America. Lake Amatitlan, Guatemala. Temperature of water 

 72"- January 1906. (Kellerman, Meek and Smith). 



84. Microcystis elabens (Meneghini) Kuetzing. Tab. Phyc. i: 6. pi. 8. 1845- 



1849. De Toni. Syll. Algar. 5: 88. 1907. 

 Farlow. Marine Algae of New England. 28. 1881. (Polycystis 

 elabens Kuetz.). Martindale. Marine Algae of the New Jersey Coast 

 and Adjacent Waters of Staten Island. Mem. Torr. Bot. Club, i: 90. 1889. 

 Collins. Algae. — Rand and Red field's Flora of Mount De-sert Island, Maine. 

 249. 1894. Collins. Preliminary Lists of New England Plants. — V. Marine 

 Algae. Rhodora. 2: 42. 1900. Collins, Holden and Setchell. Phyc. Bor.- 

 Am. Fasc. 23. no. iioi. 1903. Collins. Phycological Notes of the late 



Isaac Holden, — I. Rhodora. 7: 172. 1905. 



Plate II. fig. 19. 



Colonies spherical, oblong, or flattened, membranaceous, surrounded 

 by a common gelatinous tegument, sometimes containing several daughter 

 colonies each surrounded by its own tegument, bluish or olive-green; cells 

 i-l.S mic. in diameter, 3-5 mic. in length, oblong; cell contents showing 

 vacuoles. 



Maine. On rocky sides of a tide pool at high water mark. Cape Rosier. 

 July 1896; among small algae. Seal Harbor. (Collins). New Hampshire. 

 (Collins). Massachusetts. "Common in summer on decaying algae, over 

 v/hich it forms slimy masses." Wood's Holl. (Farlow). Rhode Island. 

 (Collins). Connecticut. On decaying algae. Fresh Pond. August. (Hol- 

 den). New York. Prince's Bay, Staten Island. (Pike). 



85. Microcystis pulverea (Wood) De Toni. Syll. Algar. S: 92. 1907. 



Wood. Contr. Hist. Freshwater Algae North America. 79. 1872. 

 (Pleurococcus pulvereus Wood). WoUe. Fresh Water Algae. 

 III. Bull. Torr. Bot. Club. 6: 182. 1877. (Anacystis glauca Wolle) ; 

 Fresh-Water Algae U. S. 329. pi. 210. f. 25. 1887. (A. pulvereus (Wood) 

 Wolle). 



Plant mass pulverulent, bright glaucous or whitish blue-green, com- 

 posed of very numerous and densely crowded colonies; colonies spherical 

 or oblong, usually surrounded by a difHuent, hyaline tegument; cells 2-3 

 mic. in diameter, somewhat spherical, oval or angular, very much crowded; 

 cell contents pale blue or olive green. 



