Herbarium specimens of R. crassipellitum show the filaments to 

 be stout, but the cells are short-cylindric and more irregular than 

 in our specimens. Also in the tropical specimens thel-e are rhizoidal 

 branches which arise from an inflated cell in the main axis. It is 

 thought that our specimens may be an aquatic form of tlie subaerial 

 typical expression of R. crassipellitum. 



Floating in sloughs and lakes. Mich., Wis. 



Rhizoclonium fontanum Kuetzing 1843, p. 261 



PI. 23, Fig. 2 



Filaments coarse, crooked or straight. Cells cylindrical but with 

 uneven lateral walls that are 1.5-2/a thick; 12-22/a in diameter and 

 up to 80yLi long. Branches multicellular, very slightly smaller than 

 the main axis. 



Tychoplanktonic mats in shallow water of lakes. Mich., Wis. 



Rhizoclonium hieroghjphicum ( C. A. Ag. ) Kuetzing 1845, p. 206 



PI. 23, Fig. 3 



Filaments long, wiry, unbranched. Cells with walls of variable 

 thickness, usually thin in the typical form; 10-52/x in diameter, 

 2^2 to 10 times their diameter in length. Chloroplast varying with 

 the age of the plant, sometimes a close net and very dense, or an 

 open reticulum. 



Common in standing water, especially in hard water lakes. Mich., 

 Wis. 



Rhizoclonium hieroghjphicum var. Hosfordii ( Wolle ) Collins 



1909, p. 169 



A variety with short, lateral branches. Filaments 36-40/a in di- 

 ameter. Cells up to 6 times the diameter in length; with thicker walls. 



Rhizoclonium hieroglyphicum and its various expressions are more 

 widely distributed and more common than any otlier species of the 

 genus in our collections. The diameter of the cell and the thickness 

 of the wall vary greatly. Some specimens agree with var. macromeres 

 Wittrock, a stout plant 20-30-(53)/x in diameter, with cells 6-12 

 times their diameter in length. Inasmuch as confusion exists within 

 the nomenclature of the various forms of this species no attempt is 

 made to assign names to the several expressions found in our region 

 other than the var. Hosfordii. At present it seems best to refer all 

 unbranched, long-jointed plants to R. hieroglyphicum. 



Mich. 



[142] 



