Chroococcacece 343 



of non-motile spores or gonidia from the contents of a mother-cell. 

 Most Algge of this family are marine, the only British freshwater 

 genus being Chamcesiphon. 



Genus Chamaesiphon A. Br. & Grun., 1864. [Indus. Sphcero- 

 gonium Rostaf., 1883.] The cells are small, ovoidal, pyriform, or 

 cylindrical, with very thin cell-walls. The cell-contents are homo- 

 geneous and of a blue-green, violet, or yellow colour. The cells 

 are attached by their base and generally widen upwards to their 

 free apex. The gonidia are successively cut off from the upper 

 part of the cell which has become a gonidangium, gradually 

 escaping from the open apex. 



Fig. 159. Chamcesiphon incrustans Grun., on a filament of Rhizoclonium, 

 from Heaton, W. Yorks. ( x 416). 



Ch. confervicola A. Br. is found as an epiphyte on Chcetomorpha, Rhizoclo- 

 nium, Vaucheria, etc., and Ch. incrustans Grun. (diam. of cells 3'5 

 fig. 159) often thickly covers filaments of Rhizoclonium and (Edogonium. 



Family 2. CHROOCOCCACEJE. 



This is the largest family of the Coccogoneae, and includes a 

 great variety of unicellular and colonial blue-green Algae. They 

 are abundant in all kinds of damp and wet situations, frequently 

 forming a gelatinous stratum on the damp surfaces of dripping 

 rocks. The cells vary much in shape in the different genera, and 

 the colonies assume different forms according to the direction of 

 division of the cells. In some the cells divide in every direction 

 of space within a gelatinous envelope, producing an irregular 

 colony, often of large size. In others the cells divide only in two 

 directions in the same plane, giving rise to a tabular colony ; and 

 in others cell-division takes place in one direction only. In one 

 genus (Tetrapedia) the cells are flattened and they possess a 

 striking symmetry of form. Synechococcus and Tetrapedia are the 

 only genera which are commonly destitute of a mucous envelope. 

 In all others the cells are invariably embedded in a mass of mucus, 



