FRKSII-\V A I ] II ALG.i: 01 THE UNITED STATES. 155 



ennrinitrr lii-xair'uiis, niiirulis in processna rectos et divergentes productis, dorso processibui 

 hiinililnis 4-;"> in.-iriirio ; .emirellulis a vert ice polygouis vel sulioruieularihuH uiuririnc proces- 

 s-Mills niimiT'iM-, |ilrniiui|iic '.' in-tni'-in ; ilorso processibus 5-8 instruct!* ; processibus omni- 

 l>ii- .Miiiilihus, granulutu-ilentati.s, apice achroo siuiplicibus, bifurcatis vel fissis. 



Diam. A venire cum proccssibus, yVoW = .00475". Sine process. iAW ~ -002". 

 Syn.St. mttnitum, Wood, Proceed. Ac. NatSc., 18G9. 

 Hub. In lacu Saco, New Hampshire; (Lewis) Wood. 



S. rather large, about one-half longer than broad, slightly constricted in the middle ; semicelle 

 fn>m the front irregularly hexagonal, the angles prolonged in straight divergent processes, 

 and the surface furni.-hed with four or five similar ones ; scmicells from the vertex polygonal 

 or siiliurhiriilar, the margin furnished with numerous processes, mostly about nine, and also 

 with 5-8 on the dorsuni ; processes all similar, granulate-dentate, their transparent apices 

 .simple, bifurcate or torn. 



k*. This species is most closely allied to St. furcigentm, Br^b., from 

 which it is at once distinguished by the orbicular vertex. The constriction between 

 thr srinirrlls is also very different. In St. iminilnm it is a gradual, not very deep, 

 hour-glass contraction ; in St. furciymtm it is very narrow and linear. 



Fig. 13 a, pi. 13, is a front view of this plant magnified 260 diameters ; fig. 13 6, 

 the c'lul view of the same. 



St. eiiwtcplianum, (K"RB.) Ii.vi.rs. 



St. laterum integrorum angulis productis apice spinulosis, spinularum furcatarum corona media 



dorsali. (II.) Species mihi ignota. 

 Syn. Desmidium euslephanum. EHRENBERO, Verbrcitung and Einfluss dcr Mikrosk. Lebcus 



in Siid- uud Nord-Amcrika, t. 4, f. 23. 



Staurastrum eustephanum, (EiiRB.) HAI.KS, British Desmidieffi, p. 215. 

 Stephanoxanthiumeustephanum, KLTZINO. UABENUOOST, Flora Europ. Algarum, Sect. 



III. p. 221. 



Nauraslriim euglephanum, UALFS. RABENHORST (loc. tit.) 

 Hab. West Point, New York ; Bailey. 



Knil view triangular with six emarginate spines on the upper surface; each angle terminated 

 by a short ray tipped with spines. (Ralfs) 



St. senarium, (EIIRB ) RALFS. 



Antecedent! simile sed laterum parictibus spinulis furcatis binis (sex), corona dorsali senaria. 

 (II.) Species mihi ignota. 



Syn. Desmidium senarium, EiiRENnER, Verbrcitung. T. IV. 



Slephanoxanthium senarium, KUTZINU. RABENHORST, Flora Europ. Algarura, Sect. III. 



p. 220. 

 Slauraslrum senarium, (EiiRB.) RAI.FS, British Desmidieas. RABENUORST, (loc. cit.) 



Segments smooth in end view with three angles, each terminating in a short process tipped by 

 minute spines, without lateral processes, but with six others confluent at their bases on the 

 upper surface, divergent and forked. (Archer.) 



Genus XANTHIDIUM, EHRB. 



Cellnlaj singular vel geminee concatenatas, inflatc-rotundatae, profunde constrict ; semicellulae 

 compress*, oblongee, hemispherice vel subquadrangnlares, centre in tnberculum rotundatum vel 

 truncatura et denticnlatum protnberantes, ex transverse oblongo-rotundatse. Cytioderma firmum 

 setis, aculeis vel spinis simplieibus aut bi- tri-furcato-divisis armatum. Massa chlorophyllacea 

 ndiatim expansa. Zygosporie arniatae. (R.) 



