filaments. Occurring as green expansions on moist substrates; aerial 

 (and aquatic ?). Branching ot filaments vestigial, not evident. 

 Chloroplast a dense, lobed parietal plate covering most of the cell 

 wall, usually containing a single pyrenoid. 



The tiue relationship of Frotococcus is debatable, and opinions 

 concerning its taxonomy are numerous. As mentioned by Smith 

 ( I.e. ) the name Protococcus is preferable to Pleurococcus Meneghini. 

 After discussing the synonymy of the genus, Pascher ( 1915, p. 223 ) 

 retains it in the Protococcales ( Chlorococcales ) as of uncertain 

 position. 



Protococcus viridis C. A. Agardh 1824, p. 13 



PI. 10, Figs. 5-7 



Characters as described for the genus; the cells 8-12- (25) /a in 

 diameter. 



Common and widely distributed on moist bark of ti"ees, on old 

 wood in subaerial habitats, and on floating (and submerged ?) 

 logs. Mich., Wis. 



FAMILY COLEOCHAETACEAE 



This family is characterized by cells bearing sheathed setae, 

 either simple or branched; the sheath a basal cylinder of firm 

 mucilage. In one genus, branched filaments are formed, which 

 may be entirely or only in part horizontal. In other forms the cells 

 may be solitary, or if multicellular, not filamentous. The chloroplast 

 is a parietal plate and usually contains a single pyrenoid. There are 

 biflagellate zoospores in asexual reproduction, whereas sexual re- 

 production is carried on by either iso- or heterogametes (oogamy). 



Key to the Genera 



1. Plants globose or hemispherical unicells (sometimes 2-celled), solitary 



or gregarious and epiphytic, each cell bearing a long, sheathed seta 2 



1. Plant a filamentous thallus, forming horizontal discs 



or cushions, or with erect, branched filaments Coleochaete 



2. Plants globose, unicellular or 2-celled, each cell 



bearing a simple, sheathed seta Chaetosphaeridium 



2. Plants hemispherical, unicellular, with a branched 



seta arising from the base of the cell Dicranochaete 



COLEOCHAETE de Brebisson 1844, p. 29 

 Plant consisting of attached, branched filaments, either entirely 

 prostrate and radiating, forming a monostromatic disc with the 

 filaments laterally adjoined or loose and spreading, or in some 

 species with erect branches. Cell wall frequently bearing a sheathed 

 seta which develops through a special pore from a blepharoplast. 



[127] 



