148 FRESH-WATER ALG^E OF THE UNITED STATES. 



A. CYTIODERMA LJEVE VEL RARISSIME SUBTILITER PUNCTATUM. 

 CYTIODERM SMOOTH OR VERY RARELY VERY FINELY PUNCTATE. 



1. Semicellularum anguli rotundati. 

 Angles of the semicells rounded. 



St. iiiiiliciiiii, BREB. 



St. a fronte orbiculare, Iseve, profunde constrictum, nudum, vel muco plus minusve firmo invo- 

 lutum ; semicellulis ellipticis, a vertice conspectis 3-4 angularibus (rarius quinquangularibus) 

 angulis rotundatis, lateribus leviter sinuato-retusis ; zygosporis aculeatis, aculeis elongatis, 

 subulatis, fureatim fissis. (R.) Species mihi ignota. 



JHam 0.0013" 0.000147". (R.) 



Syn. S. muticum, BREBISSON. RABENHORST, Flora Europ. Algar., Sect. III. p. 200. 



Hob. South Carolina ; Rhode Island ; Bailey. 



Segments in f. v. elliptic, smooth, without spines ; e. v. with three or four broadly rounded 

 angles, sides concave. Sporangium beset with numerous elongate somewhat stout spines, 

 forked at the apex. (A.) 



St. orbiculare, (EHRB.) RALFS. 



St. suborbiculare, leeve, saepius muco matricali involutum ; semicellulis divergentibtis, semi, 

 orbicularibus, dorso nonnunquam elevatis, angulis plus minus late rotundatis, lateribus plus 

 minus sinuato-retusis ; zygosporarum aculeis elongatis, subulatis, integris. (R.) 



Diam. .002". 



Syn. St. orbiculare, (EHRB.) RALFS, British Desmidieae, p. 125. RABENHORST, Flora Europ. 

 Algarum, Sect. III. p. 200. 



Hob. Rhode Island ; Bailey. Pennsylvania ; Wood. Rhode Island ; (S. T. Olney) Thwaites. 



Segments in f. v. semiorbicular, smooth, without spines ; e. v. with three broadly rounded angles, 

 sides slightly concave. (A.) 



Remarks. Fig. 17, pi. 21, represents the outline of the end view of a frond of 

 this species. Fig. 8, pi. 1 3, is a drawing of the front view of a living frond. 



2. Semicellularum anguli mucronati vel aristati. 

 Angles of Che semicells mucronate or bristly. 



St. longispinum, (BAILEY) ARCHER. 



St. magnum triangulare, laeve, angulis in aculeos geminos validos subulatos longe productum, 

 lateribus subplanum. (R.) Species mihi ignota. 



Syn. Didymocladon longispinum, BAILEY, Microscopical Observations. 



Hob. Florida; Bailey. 



"Large, smooth, triangular, with two long spines at each angle." Bailey. 



St. dejectum, BREBISSON. 



St. Ia3ve, parvum, sinu amplo, obtusangulo (vel acutangulo) ; semicellulis ellipticis (vel snbtri- 

 angularibus), dorso nonnihil convexo, utroque fine in aculeum achroum rectum vel varie cur- 

 vatis productis; a vertice triangularibus (vel quadrangularibus), angulis ssepe rotundatis 

 aculeo interdum obsolete imposito. 



IWam. Lat. TSSo* nVW' = 0008"-.001". Long. T5 ' 5 ,/ T5 VV = .0008" .0001". 



Syn. Staurastrum dejectum, BREBISSON. RABENHORST, Flora Europ. Algarum, Sect. III. 

 p. 203. 



