154 FRESH-WATER ALG^ 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 (caeterum laeve), 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 ignota. 



X)mOT._0.001"— 00089" (R.) 



Syn.—St. Hystrix, Ralfs, British Desmidieae, p. 128. Kabenhokst, Flora Europ. Algarum, 

 Sect. III. p. 213. 



5"a6.— 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 ; 

 e. V. with three or four broadly rounded angles, the spines scattered, chiefly confined to the 

 extremities, sides concave. L. ttte' — ttsW- ^'■- ttV/' — ts^"- 



St. Cerberus, (Bailey) Archer. 



St. parvum, tam longum quam latum, sinu rotuhdato, snperficie Isevi ; semicellulis oblongis 

 utroque fine sinuato-truncatis, angulis in aculeum cuspidutum productis, in medio snrsum et 

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

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

 Species mihi ignota. 



Diam—Cxim. acul. 0.00114"— 0.0013". (R.) 



Syn. — Didymocladon Gerberus, Bailey, Microscopical Observations. 



St. Gereherus, (Bailey) Archer. Rabenhorst, Flora Europ. Algar., Sect. III. p. 215. 

 Eab. — 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 plertjmque truncatis et dentato-pissis 



MTJNITUM. ' 



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

 TATELY TORN. 



St. furcigerum, Br£b. 



St. validum, subraagnum, circiter tam longum quam latum, laeve vel subtiliter granulatum, 

 plerumque profundissime constrictum, sinu angusto linear! ; semicellulis oblongo-ellipticis, 

 plus minus tumidis, angulis in processus 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 8-, 4-, 6-, T-, 8-, 9-angularibus vel 

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

 productis. (R.) Species mihi ignota. 



Long. Sine process, 0.0018"— 0.0019" ; c. pr. 0.00.3"'— 0.0032". Lat. sine proc. 0.00185"; 

 c. pr. 0.0027". (R.) 



Syn. — Staurastrum furcigerum, BRfiBissoN. Rabenhorst, Flora Europ. Algar., Sect. III. 

 p. 219. 



Didymocladon furcigerus, Ralps, British Desmidiese. 

 Eab. — South Carolina ; Florida ; Rhode Island ; Bailey. 

 St. innnitum, Wood. 



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



