SPECIES OF ALG^. 43 



14. PRASIOLA. 



Tufts 2-6 mm. high and broad, cells 4-6jx in diameter, crispa, io6 

 " 1-3 inches long and broad, cells 6-8/t " " 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 jomt (a), 

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

 seta ... . . . .... . spinosa, 109 



a. Branches opposite or alternate . glomerata, io?>, plumosa, 1-09 



17. STIGEOCLOklUM. 



§ 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. Pa.rasitic, dwarf, 2 mm. long; in mucus .... radians, 115 



d. Not parasitic (e). 



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



e. " " " " 25-40/^ . . . nudiusculum, 113 



f. Diameter of filaments ii-20yu; basal cells 6-8 times longer than 



wide . ... subsecundum, 112 



/. Diameter of filaments io-i6/i {g). 



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



flagelliferum, 112 

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



h. Upper branches clustered, moniliform . fasttgiatum, 114 



h. " " not moniliform (j). 



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



fasciculare, 114 



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



clustered longipilus, 115 



