No. IO.] FRESH-WATER ALGJE. 1 3 



Aphanothece Nag-. Very like Glocothece, with cells 

 longer than broad ; but the teguments are confluent, forming 

 a firm gelatinous body which encloses the cells. 



Microcystis Kiitz. (Polycystis Kiitz. ; Clathrocystis 

 Henfrey). Numerous small cells gathered into globular, ob- 

 long or irregular families, each with a thin tegument, usually 

 single but sometimes associated with other families, and all en- 

 closed in a common tegument. The cells divide alternately in 

 three directions. 



M. ceruginosa (Kiitz.) (?), Figs. 9, ga. Sometimes very 

 abundant in reservoirs and giving an unpleasant taste to the 

 water. Frequently thus associated with Anabcrna. 



Ccelosphaerium Nag. Thallus hollow, spherical, with 

 numerous small spherical cells in families, or scattered at the 

 periphery, embedded in a gelatinous stratum. Multiplication 

 takes place by means of enlarged cells which escape and form 

 daughter-cells, or by constriction and division of the mother- 

 cells. 



C. Kuetsingianum Nag., Fig. 7. 



Gomphosphaeria Kiitz. A globose, free, floating thallus, 

 composed of wedge-shaped cells, in pairs, associated in radi- 

 ating families at the periphery of a solid gelatinous sphere, and 

 furnished with a tegument. The cells divide alternately in 

 three directions. 



Gloeocapsa Kiitz. Cells blue-green, steel-blue, reddish, 

 yellowish, etc., spherical or oblong, with a wide, bladder-shaped 

 integument. The cells divide into two daughter-cells, each 

 furnished with a tegument and both surrounded by the tegu- 

 ment of the mother-cell. The cell membrane is very thick, 

 often lamellated, and the strata frequently separate; either 

 colorless or colored. 



G. arenaria (Rab.) ( ?), Figs. 8, 8a. The specific distinc- 

 tions in this genus are very uncertain. 



[G. violacea (Chorda) Rab.] 



Aphanocapsa Nag. Cells spherical, with a thick, soft 

 tegument; cell division as in Gloeocapsa, but individual coats 

 not evident around the cell. 



