SPECIES OF ALG^E. 43 



14. PRASIOLA. 



Tufts 2-6 mm. high and broad, cells 4-6^ in diameter, crispa, 106 

 " 1-3 inches long and broad, cells 6-8jn " " Mexicana, 107 



15. ENTEROMORPHA. 



In brackish water (a). 



a. Fronds simple, elongate; cells 3-5-6 angled . . intestinalis, 107 



a. " compressed, tubular compressa, 107 



16. DRAPARNALDIA. 



A. Every mature joint with 2-4 clusters of branches, Ravenellii, no 



A. Branches less abundant, not at every joint (a). 



a. Branches opposite, their stems thick, short, tapering to a point or 



seta spinosa, 109 



a. Branches opposite or alternate . . glomerata, io&,fltum0sa, 109 



17. STIGEOCLONIUM. 



In warm or hot water; 1-2 in. long, much branched, apex a bristle, 



thermale, in 



Not in water of high temperature (a). 

 a. Branches ending in a hair or bristle (b). 



a. Branches not ending in a hair or bristle (k). 



b. Bristle a colorless, apparently hollow prolongation (c\ 



b. Bristle a delicate, filamentous, hair-like extension (d). 



c. Cells nearly cylindrical, equal or twice as long as broad, 



protensum, 112 



d. Parasitic, dwarf, 2 mm. long; in mucus radians, 115 



d. Not parasitic (e). 



e. Diameter of largest cells 20 jt or less (/). 



e. " " 25-40^ nudiusculum, 113 



f. Diameter of filaments i i-2o//; basal cells 6-8 times longer than 



wide subsecundum, 112 



f. Diameter of filaments io-i6// (g). 



g. Branches opposite on cells smaller and more oval than the others, 



flagelliferum, 112 



g. Branch-bearing cells not smaller (//). 



h. Upper branches clustered, moniliform .... fastigiatiim, 114 

 h. " not moniliform (/). 



j. Two or more inches long, branches mostly opposite, 



fasciculare, 114 



j. Two to 10 mm. long, simple to near the end, there branches 

 clustered longipilus, 115 



