106 SPECIES OF DESMIDS. 



aa. Apices of rays obtuse; diameter -^ to -^ in. (40-50/^), 



arachne, 129 



aa. " " " diameter T^ to TiW in- (15-20/^). 



iotanum, 137 

 ■aa. Apices of rays not obtuse {bV). 



hb. End of cell in front view papillose or verrucosa (cc). 

 bb. " " " " not papillose nor verrucosa (dd). 

 tc. Diameter ,5-^^ in. (36/^) or smaller, arcuatum,T.T,o; subarcuatum, 140 

 ic. " -j-J^ to ^^ in. (6o-8o/<) ; arms diverging, anatinum, 139 

 ■dd. End view, sides straight, angles 3-4 spinous,, polymorphum, 126 

 dd. " sides concave; arms long, straight, in front view di- 

 verging paradoxum, 129 



■dd. End view, sides concave; arms short, Haabxliense, 131; nanum, 138 

 dd. " sides convex; arms short, tumid at base, .^if/^a;'««»z, 133 



£e. Apices of arms inconspicuosly bifid or trifid, 



Haabceliense, \j,\; paradoxum, 129 

 ■ee. Apices of arms prominently and deeply trifid . . . Osceolense.* 



ff. Apices of arms obtuse; the arms mere lobes, very short, 



silataium, 128 

 ff. " " " arrns long, narrow .... arachne, 129 



ff. Apices of arms bifid; front yiew end with a crown of papillae, 



Floridense, 135 

 ff. Apices of arms bifid; front view end without papillae, 



pentacladum, 136 



gg. End view 4, 5, 6, or 7-angular or radiate (lih). 

 gg. End view triangular (zV). 



hh. Cytioderm rough with pearly granules; rays 4-7, short, obtuse, 



maigaritaceum, 125 

 hh. " granulate; end view 4-6 angled, sides straight, 



Meriani, 132 

 ////. " ■' end view 4 angled, angles with 2 spine^ 



Novce CasarecB, 145 



hh. " " end view 4-5 angled, sides concave, angles 



without spines dilatatum, 128 



a. Angles in front view notched or otherwise divided {jj). 



a. Angles entire (kU). 



*Bulletin Torrey Botanical Club, Dec. 1885. 



