154: FRESH-WATER A L G JE OF THE UNITED STATES. 



Segments in f. v. semiorbicular, separated by a linear constriction, covered with very minute, 

 very numerous close set hair-like spines ; e. v. with three broadly rounded angles, the spines 

 evenly and numerously scattered ; sides slightly convex. Sporangium orbicular, beset with 

 short spines, branched at the apex. (A.) 



St. Hystrix, RALFS. 



St. parvum, tertiam partem longius quam latum, angulis aculeatum (cseterum loevc), sinu acu- 

 tangulo ; semicellulis subquadratis, angulis late rotundatis, dorso planis, a vertice 3-4 angu- 

 laribus, angulis late rotundatis, plus minus dense aculeatis. (R.) Species mihi ignola. 



Diam.0.00l"0 00089". (R.) 



Syn. St. Hystrix, RALFS, British Desmidieae, p. 128. RABENUORST, Flora Europ. Algarum, 



Sect. III. p. 213. 

 ffab. Rhode Island ; (S. T. Olney) Thwaites. 



Segments in f. v. subquadrate, extremities somewhat rounded, end margin nearly straight, fur- 

 nished with a few scattered, subulate, acute spines, chiefly confined to the lateral extremities; 

 c. v. with three or four broadly rounded angles, the spines scattered, chiefly confined to the 

 extremities, sides concave. L. T nVi?" nrW- Br - nW ffk"- 



St. Cerberus, (BAILEY) ARCHER. 



St. parvum, tarn longum quam latum, sinu rotundato, snperficie laevi ; semicellulis oblongis 

 utroque fine sinuato-truncatis, angulis in aculeum cnspidutum productis, in medio sursum et 

 deorsum prominentiis geminis in aculeum elongatis instructis, a vertice triangularibus, angulis 

 in apice truncate- vel sinuato-bi-cuspidatis, sub apice aculeis geminis brevibus praditis. (R.) 

 Species mihi ignota. 



Diam.Cum. acul. 0.00114" 0.0013". (R.) 



Syn. Didymocladon Cerberus, BAILEY, Microscopical Observations. 



St. Cereberus, (BAILEY) ARCHER. RABENHORST, Flora Europ. Algar., Sect. III. p. 215. 

 Hob. Florida ; Bailey. 



Small, deeply constricted, segments three-lobed, lobes with four teeth, two of which project 

 upwards and two downwards at each truncated angle. (A.) 



D. CYTIODERMA PROCESSIBUS NUMEROSIS, APICE PLERUMQUE TRUNCATIS ET DENTATO-FISSIS 



MUNITUM. 



CYTIODERM WITH NUMEROUS PROCESSES, WHOSE APICES ARE MOSTLY TRUNCATE AND DEN- 

 TATELY TORN. 



St. ftircigeruin, BREB. 



St. validum, subraagnum, circiter tarn longum qnam latum, laeve vel subtiliter granulatnm, 

 plernmque profundissime copstrictum, sinu angusto lineari ; semicellulis oblongo-ellipticis, 

 plus minus tumidis, angulis in processns bifurcum aut rectum aut divergentem longe pro- 

 ductis, dorso processibus similibus 2, 3, 4, instructis, omnibus processibus achrois granulato- 

 dentatis, granulis in series transversas ordinatis, a vertice 3-, 4-, 6-, 7-, 8-, 9-angularibus vei 

 radiatis, angulis plus minus tumidis, in processus crassum achroum asperum in apice fissuin 

 productis. (R.) Species mihi ignola. 



Long. Sine process, 0.0018" 0.0019" ; c. pr. 0.003'" 0.0032". Lat. sine proc. 0.00185"; 

 c. pr. 0.0027". (R.) 



Syn Stauraiitrum furcigerum, BREBISSON. RABENHORST, Flora Europ. Algar., Sect. III. 

 p. 219. 



Didymocladon fur tigerus, RALFS, British Desmidieae. 

 ffab. South Carolina ; Florida ; Rhode Island ; Bailey. 

 St. miinil urn. WOOD. 



St submagnum, fere plo longius quam .atum, medio leviter constrictum, semicellulis a fronte 



