346 Myjcophycece 



of which a new colony is developed from the side of the old one, 

 ultimately becoming separated from it. Cell-division may be in 

 one direction only, in two directions in one plane, or in every 

 direction of space. 



Reproduction occurs in Gomphoaphceria by non-motile spores 

 or gonidia 1 . 



There are thirteen British freshwater genera, which can be arranged as 

 follows : 



A. Cell-division in one direction only. 

 * Cell-division transverse. 



t Cells enveloped in a wide mucous coat. 



\ Cells elongated, each with a mucous coat Gloeothece. 



\\ 



Cells little longer than broad, enveloped 



in a common mucous investment ... Aphanothece. 

 t 1 Cells destitute of mucus ........................ Synechococcus. 



** Cell-division oblique ; cells enveloped in mucus Dactylococcopsis. 



B. Cell-division in two directions in one plane. 



* Cells globular or rounded-quadrate ; colonies 



often large ............................................. Merismopedia. 



** Cells of a definite symmetrical form, solitary, 



or forming small colonies ........................ Tetrapedia. 



C. Cell-division in all directions of space ; cells enveloped in mucus. 



* Cells forming large colonies. 



t Cells arranged at or towards the periphery of spherical 



colonies. 



J Cells closely and regularly arranged ... Codosph<xrium. 

 \\ Cells geminate and sparsely scattered, 



markedly pyriform in shape ............ Gomphosphcena. 



tt Cells densely aggregated in globose, elon- 



gated, or clathrate colonies ............... Microcystis. 



ttt Cells aggregated to form irregular gelatinous colonies. 

 j Individual mucous coats clearly evident 



round each cell ........................... Glceocapsa. 



\\ Cells enveloped in a common mucous 



covering .................................... Aphanocapsa. 



JJ| Cells arranged in a compact gelatinous 



stratum .................................... Porphyridium. 



** Cells more or less solitary, or forming very 



small colonies ....................................... Ckroococcus. 



Genus Gloeothece Nag., 1849. The cells are cylindrical and 

 elongated, each one being surrounded by a thick mucous coat, 

 which sometimes shows indications of lamellation. Cell-division 



1 Schmidle in Berichte Deutsch. Botan. Gesellsch. 1901, xix. 



