FRESII-WATER ALG^ OF THE UNITED STATES. 129 



Z)/flm.— Semicell, 0.0019"— 0.0022". (R.) 



Sijn. — C. Brebissonii, Menegheni. Rabenhorst, Flora Europ. Algarum, Sect. III. [). 158 



Hah. — White Mountains, New Hampshire, (Dr. F. W. Lewis) Wood. 



Frond somewhat longer than broad, constriction deep, linear; segments semiorl)ieular, rough 

 all over, with somewhat elongate conical scattered pearly granules ; e. v. elliptic. (A ) 



Rcmarlc. — Fig. 6, pi. 21, represents an empty frond of this species, magnified 

 750 diameters. 



C suborbiciilare, Wood. 



C. parvuni, suborljiculare, paulo longius quam latum, cum margine euormiter crenato vel 

 crenato-undulato; semieollulis a latere orbicularibus, a vertice ellipticis; sinu e.xtrorsum 

 angustissimo sed iiitrorsum nounihil excavato ; cytiodermate crasso, sparse vcrruculoso ; 

 granulis in seniicellulis singulis subdistantibus et in seriebus elongatis, duabus (iuterdum 

 unica) esternis curvatis, et in seriebus duabus interni.s brevibus ct rectis. 



Diam.—Lat. t^Vsu" = -0012" ; lat. tij'/us" = -0013". 



8yn. — C. orbiculare, Wood, Proceed. Acad. Nat. Sc. 18Y0. 



Hab. — In lacu "Saco," New Hampshire, (Lewis.) 



Small, suborbicular, a very little longer than broad, with the margin irregularly crcnate, or 

 creuate undulate ; semicells from the side orbicular, from the vertex elliptical ; sinus very 

 narrow, but within somewhat excavated ; cytioderm thick, sparsely coarsely granulated ; 

 granules subdistant, in each cell arranged in one or two curved marginal series and in a cen- 

 tral group of two or three short rows. 



Een-arks. — The arrangement of the granules in this desmid is peculiar, one, or 

 sometimes two rows of large obtuse pearly granules are placed at rather wide in- 

 tervals along the whole outer margin, and then in the centre of each semiccll is a 

 group of two or three, or even more short straight rows of three or four similar 

 but rather smaller granules. The isthmus is rather broad and short; sometimes it 

 las on it one or two granules. 



Fig. 9, pi. 21, represents an empty frond of this species, magnified 750 diame- 

 ters ; 9 a, the outline of the end view of the same. 



C. tetrophthalniiim, (Ktz.) Breb 



C. tcrtiam partem circa longius quam latum, profundc constrictura ; sinu angusto, plcrumquc 

 sublineare ; ambitu obtuse crenato; semicellulis nonnihil semicircularibus, ventre subplauis, 

 dorso rotundatis; cytiodermate verruculoso ; verruculis maguis, obtusis, subordinatim dispo- 



sitis. 



Syn. — C. tetrophthahnum, (Kcitzing), Br^bisson. Rabenhorst, Flora Europ. Algarum, Sect. 

 III. p. L59. 



Hah. — New Jersey ; Wood. 



About one-third longer than broad, deeply constricted ; sinus narrow, mostly sublinear; margin 

 obtusely erenated ; semicells somewhat semicircular, belly nearly even, dorsum rounded; 

 cytioderm warty ; prominences large, obtuse, arranged somewhat regularly. 



Remarlcs. — The only specimens I have seen, and I believe the only ones hitherto 



17 July, 1872. 



