FRESH-WATER A L G^ O F T H E U i\ 1 T E D S T A T E S. 151 



e. V. tri-or quadriradiate, processes short, usually colorless, sides somewhat concave. >Spo- 

 rangium orbicular, beset with spines ultimately branched at the apex. L. i^j^" — gjj". 



Bi " 



2. Semicellulae triangulares; anguli non producti, obtusi vel rolundati. 

 Semicells triangular ; the angles not produced, obtuse or rounded. 



St. piinctiilatuiu, Breb. 



St. parvum, punctulato-granulosum; scmrcellulis enormiter ellipticis, dorso lato rutuudatis, a 

 vertice triangularibus ; angulis non productis, obtuse rotuudatis ; lateribus uiodice retusis. 



Diavi.—L&t. T5'^"=.0012". 



Syn. — S. punctulatum, Bkebisson. Ralfs, British Desmidiese. Rabenhorst, Flora Europ. 

 Algarum, Sect. III. p. 208. 



Ilab. — Pennsylvania ; Wood. 



Small, punctulate-grannlate ; semicells irregularly elliptic, with the dorsum broadly rounded 

 from the vertex triangular; angles not produced, obtusely rounded; sides somewhat retuse. 



Remarks. — This desmid is exceedingly common around Pliiladelphia, growing 

 in the greatest abundance upon the face of wet dripping rocks. It is represented, 

 % 10, pi. 13. 



St. crenatum, Bailey. 



St. duplo circiter longius quara latum, in medio utrinque esscctione profunda rotundata ; 

 semicellulis e basi cuueata ilabelliformibus, margiue superiore crenatis, a vertice triangularibus, 

 angulis rotundato-truncatis, crenatis, lateribus siiiuatis glabris. (B.) Species mihi ignota. 



Syn. — St. crenatum, Bailey. Ralfs, British Pesmidieaj, p. 214. Rabenhorst, Flora Europ. 

 Algarum, Sect. III. p. 220. 



" Segments cuneate ; outer margins crenate ; end view with three truncate and crenate angles." 



3. Semicellulas vertice 3-7 radiatee ; radii in apice plerumque bi- tri- fidi vel bi- tri- spini. 

 Semicells 3-7 radiate at the vertex ; radii bi- ortri-fid, or bi- or Iri-spinous at the aptex. 



St. polyiiiorphiini, Breb. 



St. semicellulis ellipticis, subtiliter grannlatis vel tenuissime spinulosis, in medio magis minusve 

 inflatis, baud raro ventricosis, rectis, nonnunquam incurvis, utrinque proccssu plus minus 

 elongato, lineari, in apice 3-4 fido vel spinulis 3-4 tcnuissimis instructis, a vertice 3-4—5-6-7 

 radiatis, radiis achrois, aut trifidis aut rotundatis, trispinis. (R.) Species mihi ignota. 



Syn. — St. polymorphum, Brebisson. Ralfs, British Desmidieaj, p. 135. Rabenhorst, Flora 



Europ. Algarum, Sect. III. p. 209. 

 X»m?7i.— Long. 0.001". Lat. 0.00087". (R.) 

 Hab. — Florida; Bailey. 



Segments in f. v. broadly elliptic or almost circular, rough with minute granules (sometimes 

 with a few minute scattered spines), processes short, stout, tipped by three or four divergent 

 spines ; e. v. with three, four, five, or six angles each produced into a short, stout process. 

 Sporangium orbicular, beset with elongate spines, forked or branched at the apex. Archer. 



Var. CTl'tocei'lllll. {St. cyrfocerum. Breb.) 

 Majus, ad gV", longum, semicellulis introrsum ventricosis, dorso late rotundatis, utrinque pro- 

 cessu elongato, plerumque incurvo apice bi- vel tri-cuspidato instructis, a vertice triradiatis, 

 radiis rectis vel leuiter curvatis, in apice aut bi- aut tri-cuspidatis. (11.) 



