Figure 59 



HOW TO KNOW THE FRESH-WATER ALGAE 



71b Cells bean-shaped or oblong, reproducing by autospores which are 

 retained within the enlarged mother-cell wall (the wall may gela- 

 tinize and appear as a mucilaginous sheath). Fig. 59 



NEPHROCYT1UM 



Fig. 59 a, Nephrocytium ecdysiscepa- 

 num W. West; b, N. obesum W. & G. 

 S. West; c, N. limneticum (G. M. 

 Smith) G. M. Smith; d, N. lunaium W. 

 West. 



Most of the five species of this genus 



which occur in the United States have 



reniform or bean-shaped cells, often with 



one convex wall and one flattened or 



less convex than the other. They occur 



in mixtures of algae in the tychoplank- 



ton but two species of the genus, N. 



Agardhianum Naeg. and N. limneticum 



G. M. Smith are usually found in the euplankton. The former has 



elongate, almost vermiform cells which are sometimes curved or spirally 



twisted. 



72a Cells in linear pairs, 1 or several pairs within a common mucilagin- 

 ous investment (cells with long axes approximately parallel, some- 

 times solitary). See Fig. 38 ELAKATOTHR1X 



72b Cells arranged in parallel bundles, reproducing by autospores 



(daughter colonies forming within the mother-cell). Fig. 60 



QUADRIGULA 



Fig. 60. Quadrigula Chodati (Tan- 



ner-Fullman) G. M. Smith. 



There are 3 species found in 

 the euplankton of lakes, all of 

 which have elongate, fusiform or 

 'cigar'-shaped cells. The species 

 illustrated has cells with bluntly 

 rounded poles whereas the other 

 two have pointed apices. The 

 cells occur in rather compact bun- 

 dles of 4, all lying parallel in the 

 colonial envelope. 



Figure 60 



73a (38) Cells (or some of them in the colony) bearing long, gelatinous 

 bristles or scales, or hairs 74 



73b Cells without bristles but some with spines shorter or longer than 

 the cell 76 



50 



