144 FRESH-WATER ALG^ OF THE UNITED STATES. 



shorter than the diameter ; upper divisions more or less 

 elongated. Cell-membrane thick, firm subcartilaginous, lamel- 

 lose. Cell contents green, finely granular. 



Species of Chaetomorpha are frequent on our Atlantic and 

 Pacific coasts, rarely also in brackish water, but being so evi- 

 dently marine plants, the names of species are omitted. 



Plate CXXY, fig. 11, the natural size and mode of growth 

 of a smaller species ; fig. 12, part of a single filament of Chaet. 

 sutoria, Berk., magnified; fig. 13. part of a filament of a 

 larger species, (Chaet. litorea, Harv.,) enlarged, showing 

 (fig. 14,) the escape of the zoogonidia. 



Genus 29, RHIZOCLCmUM, Kg. 



Articulate threads, the same as in Conferva, but somewhat con- 

 torted, having, here and there, short rhizome-like lateral pro- 

 cesses, seldom composed of more than three cells, often only one. 



KmZOCLONIUM HIEROGLYPHICUM, Kg. 



Vegetative green, or yellowish green, forming thin webs 

 or mats of considerable extent on moist ground. Cells 14-3 

 times as long as the diameter. 



Diameter of filaments, 20-25 yw, rarely 29 /*. 



On moist or wet ground in vicinity of springs. 

 Plate CXXI, figs. 29, 30. 



Yar. AMERICANA, Wolle. 



Filaments average rather stouter, and cells rather longer 

 and more irregular in outline, than the typical plant. 



Forms close and crisped web-like growth on shaded garden 

 soil. Lateral processes unicellular. 



Plate CXXI, figs. 31, 32. 



EHIZOCLONIUM FONTINALI, Kg. 



Bright green, loosely interwoven ; diameter -of filaments, 

 13-15.5 yw. Articulations ordinarily twice as long as wide; 

 ante-division four times as long ; membrane thin. Rhizome- 

 like processes usually 2-3 -celled. 



Syn. Wiizo. fontanum, Kg. ; BMzo. rivulare, Kg. 

 Springs and flowing waters. 



Plate CXXI, figs. 22-25. 



