FKKSII-\V AT i: II ALO. OF T II K U X I T K I> SI ATI: S. 127 



Cells 3-4 angular or com pressed, not constricted, their lateral margins plain or crenatc, conjoined 



into angular jterforutrly articulate fascia. 



A. liailfvi, KALFB. 



" Filament not crcnated ; joints aboat equal in length and breadth. 



Syn. Odontellaf tridentata, BAILEY. In lit. cum icone (1846). 



Hob. Worden's Pond, Rhode Island; near Princeton, New Jersey, with sporangia," Bailey. 



" Filament triangular; joints excavated at their junction like those of Aptogonum desinidium- 

 Tin- joints an; not bicrcnate, hence the margins of the filament are entire, a character which 

 distinguishes it from that species. The cud view is triangular, with rounded angles." HALTS, 

 lirtiish. Dcsmidicse, p. 208. 



Genus COSMARIUM, (CoBDA) 



Cellulffi oblonge, oblongo-cylindricae, cllipticie, vcl orbicolarcs, medio transverse plus minus con- 

 strict, utroque polo obtusie vel rotundatffi et Integra, a vertice elliptic. Zygosporac muricaUe vel 

 Terrucosse. 



Culls oblong cylindrical, elliptical or orbicular, more or less transversely constricted in the middle, 

 olitu.se or rounded, and entire at each cud, viewed from the end elliptical. Zygospore warty or 

 muricate. 



1. Cellulee sejunctse. 



1. Cells separate. 



a. Cellulte ellipticae, vel subelliplicse ; semiccllulse medio nonventricosa. 



a. Cells elliptical or subelliplical ; semicells medianly not ventricose. 



* Cytiodermate granuloso vel verruculoso. 



* Cytioderm granular or warty. 



C. iiinrsarilifcriini, (TUBP.) MENOR. 



C. paulo longius quam latum, profunde constrictnm ; sinn amplo, vel modice angusto, intcrdiim 

 intra cxcarato; semiccllnlis semiorbicularibus, rcl rcniformibus vel nonuihil quadrangulis 

 dorso plcrumque late rotundatis ; cytiodennate verruculoso. 



Diam. Max. , -fa" = .0006" (0.00073" 0.0012". R.) 



Sijn. Euastrum margaritiferum, EHRB. BAILEY, Silliraan's Journal, 1841. 



Cosmarium margaritiferum (TuBPix), MENEGIIINI. KABENHORST, Flora Europ. Algar., 

 Sect III. p. 157. 



Hab. In aqnis quietis, South Carolina ; Florida ; Mexico ; Bailey. Pennsylvania, Wood. 



A little longer than broad, profoundly constricted ; sinus ample or moderately narrow, some- 

 times widened on the inside; semicells seniiorbicular, reniform or somewhat quadrangular ; 

 dorsum mostly broadly rounded ; cytioderm warty. 



Remarks. I have found a form of this species growing in the vicinity of this 

 rity, which I at first was disposed to look upon as distinct, but which, in truth, 

 grades into the typical form. In it the cells are almost quadrangular, often with 

 their basal angles acute. The margin of the frond in C. margaritiferum, as it 

 occurs with us, is sometimes distinctly serrate or, more correctly, crenulate from 

 the presence of the granulations. The granules are larger than in C. botrytis, but 

 smaller than in C. tetrophthalmum. When viewed laterally the semi-cells are 

 roundish, or nearly so (according to Ralfs' elliptical), and closely connected by 



