151 FllKSU-WATER A L G .E OF THE UNITED STATES. 



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

 very miinerous close set hair-lilie spines ; e. v. witlj tliree broadly rounded angles, the spines 

 evenlv and numerously scattered ; sides slightly convex. Sporangium orbicular, besel wiib 

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



St. Hystrix, R.vlfs. 



St. parvum, tertiam partem longius quam latum, angulis aculeatum (cseterum L-eve), sinu aeu- 

 tangulo ; seniicellulis subquadratis, angulis late rotuudatis, dorso planis, a vcrtice 3-4 angu- 

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



Z)mw.— 0.001"— 00089". (R.) 



Si/7i. — St. Hystrix, Ralfs, British DesmidieiE, p. 128. Rabenhorst, Flora Europ. Algarum, 



Sect. HI. p. 213. 

 //a6.— Rhode Island ; (S. T. Olney) Thwaites. 



Segments in f. v. subquadrato, e.xtremities somewhat rounded, end margin nearly straight, fur- 

 nished with a few scattered, suliulate, acute spines, chiefly conlined to the lateral extremities; 

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

 extremities, sides concave. L. tq\s" — toV^"- l*''- ttVs" — ?ri"' 



St. Cerberus, (B.\ilet) Archer. 



St. parvum, tam longum quam latum, sinu rotundato, superficie tevi ; semicellulis oblongis 

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

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

 in apice truncato-vel siuuato-bi-cuspidatis, sub apice aculeis geminis brevibus prteditis. (R.) 

 Species mihi ignola. 



Diam.—Qnm aoul. 0.00114"— 0.0013". (R.) 



Sijn. — Didymocladon Cerberus, Bailey, Microscopical Observations. 



St. Cereberus, (Bailey) Archer. R.ibeniiurst, Flora Europ. Algar., Sect. III. p. 215. 

 Ilab. — 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 

 MUNITUiM. 



CyTIODERM with numerous processes, whose APICES ARE MOSTLY TRU.NCATE AND DEN- 



tately torn. 

 St. fiircii^eriiiii, Breb. 



St. validum, submagnum, circiter tam longum quam latum, IsBve ve! subtiliter grannlatura, 

 plerumque profundissime constrictura, sinu angusto lineari ; semicellulis oblongo-elliptiei.s, 

 plus minus tumidis, angulis in processus bifurcum aut rectum aut divergentera longe pro- 

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

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

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

 productis. (R.) Species milt i. ignota. 



. Long. Sine process, 0.001S"_0.0010" ; c. pr. 0.003"'— 0.0032". Lat. sine proe. 0.00185"; 

 c. pr. 0.002Y". (R.) 



Syn —Slaurastrum furcigerum, Breiusson. Rabenhorst, Flora Europ. Algar., Sect. Ill 

 p. 219. 



Didymocladon fur cigerus, Ralfs, British Dcsmidies. 



77a&.— South Carolina; Florida.; Rhode Island; Bailey. 



St. iniinitiiin, Wood. 



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



