HOW TO KNOW THE FRESH-WATER ALGAE 



74a Cells arranged in a quadrate colony of 4 cells interconnected by 

 strands, each cell bearing a scale-like fragment of mother-cell wall. 

 See Fig. 43 CORONASTRUM 



74b Colony formed otherwise 75 



75a Cells forming an attached, compact cluster within the mother-cell 

 wall which bears a branched hair that has no sheath. Fig. 61. 



DICRANOCHAETE 



Fig. 61. Dicranochaete renitormis Heiron. 



Although this curious plant usually occurs 

 as single cells, the individuals may be clus- 

 tered as a result of recent cell division. It 

 grows on filamentous algae and other sub- 

 merged aquatic plants and apparently is very 

 rare. The unique branched seta which is pro- 

 duced from the lower side of the cell makes 

 identifications certain. 



Figure 61 



75b Cells loosely arranged side by side in a cluster, each bearing an 



unbranched hair with a basal sheath. Fig. 62 



CHAETOSPHAERID1UM 



Fig. 62. Chaetosphaeridium globosum 

 (Nordst.) Klebahn. a, group of cells; 

 b, one cell showing tube-like utricle 

 which may extend from one cell to an- 

 other and so form a sort of colony. 



This globular, hair-bearing cell occurs 

 eithor singly or in aggregations of 2 to 8 

 individuals on larger algae, on Utriculaiia 

 or on other aquatic plants. This genus 

 and Dicranochaete (Fig. 61) are anomal- 

 ous members of a family of filamentous algae. Their inclusion in the 

 Coleochaetaceae is based upon the type of seta (a bristle with a 

 sheathed base) which they have in common. 



Figure 62 



76a (73) Cells attached at the ends of branching gelatinous stalks, 



77 

 epizoic on microcrustaceans 



76b Cells not at the ends of branching gelatinous strands; not epizoic . 78 



51 



