WISCONSIN PHYTOPLANETON 61 



ANABAENA LEMMERMANNI P. Richter. PI. 10, Fig. 8; PI. 11, Fig. 1. 



Forschungsbr. a. d. Biol. Stat. zu Plon 10: 153. 1903. 



Anabaena flos-aquae Klebahn non (Lyngbye) de Breb., Flora 8O: 267, pi. 4, 

 Jigs. 21-22. 1895. 



Filaments free-floating ; irregularly or circinately interwoven to form 

 a spherical or broadly ellipsoid mass, with filaments frequently radiat- 

 ing in loops from a common center. Vegetative cells spherical or 

 slightly elongate, usually containing numerous pseudovacuoles. Heter- 

 ocysts spherical, approximately the same size as the vegetative cells. 

 Spores cylindrical, with rounded ends, with inner side straight and the 

 outer convex ; rarely remote from heterocysts, generally forming short 

 catenate series on both sides of heterocysts and lying in a dense mass 

 at the center of the colony. The spore masses and heterocysts fre- 

 quently persisting long after the disappearance of the vegetative cells. 

 ( Euplanktont) . 



Vegetative cells 5.5-7 p broad, 5-8 n long; heterocysts 6-7.5 p. broad; 

 spores 8-11 n broad, 19-33 /x long. 



Crawling Stone (rr), Diamond (r), Kawaguesaga (rr), Long (rr), Marl 

 (r), Oconomowoc (r), Paddock (cc), Palmer (r), Pardee (ss), Rainbow (2) 

 (rr), Reserve (r), Rice (1) (s),iSand (2) (rr), Taylor (ss), Trout (s). 



The species differs from A. flos-aquae in the regular looping of the 

 trichomes from a common center and the development of a large mass 

 of spores at the center of the colony. The persistence of the spores 

 after the disappearance of the vegetative cells is very common and 

 certain of the records for the species are based upon observation of the 

 spore masses only. 



APHANIZOMENON Morren 1838. 



Trichomes straight slightly flexed, or curved ; in lateral contact with 

 one another to form small, macroscopic, free-floating, feathery, plate 

 or scale-like opaque colonies. Trichomes destitute of a gelatinous 

 sheath, sometimes constricted at cross walls of cells, and slightly attenu- 

 ated at the apices. Cells cylindrical, with flattened ends. Heterocysts 

 intercalary, cylindrical. Spores elongate, cylindrical and with flattened 

 ends; solitary, adjacent to or remote from the heterocysts. 



Reproduction by the formation of hormogones and resting spores. 



APHANIZOMENON FLOS-AQUAE (L)Ralfs. PI. 11, Figs. 2-4. 



Ann. & Mag. of Nat. Hist. 2 Ser. 5: 340, pi. 9, fig. 6. 1850; Klebahn, Flora 80: 

 271, pi. 4, figs. 27-30. 1895. 



Trichomes straight or slightly curved, laterally joined to form a flat 

 flake- or scale-like plate. Cells cylindrical, with flattened ends, about 



