FRESH-WATEE, ALGM OF THE UNITED STATES. 129 



i5iam.— Semicell, 0.0019"— 0.0022". (H.) 



Syn. — C. Brebissonii, Menegheni. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 158. 



Hab. — ^White Mountaius, New Hampshire, (Dr. F. W. Lewis) Wood. 



"Frond somewhat longer than broad, constriction deep, linear; segments semiorbicular, rough 

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



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

 750 diameters. 



C. suborbicnlare, Wood. 



C. parvum, suborbiculare, paulo longius quam latum, cum margine enormiter crenato vel 

 crenato-undulato ; semicellulis a latere orbicularibus, a vertice ellipticis; sinu extrorsum 

 angustissimo sed introrsum nonnihil excavato ; cytiodermate crasso, sparse verruculoso ; 

 granulis in semicellulis singulis subdistantibus et in seriebus elongatis, duabus (interdum 

 unica) externis curvatis, et in seriebus duabus internis brevibus et rectis. 



IHam.—La.t. Wvws" = -0012" ; lat. tsA/ = -0013" 



Syn. — G. orbiculare, Wood, Proceed. Acad. Nat. Sc. 18t0. 



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



Small, suborbieular, a very little longer than broad, with the margin irregularly crenate, or 

 crenate undulate ; seraicells 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. , 



BemarJes. — 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 semicell 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 

 bias 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. tetrophthalmum, (Ktz.) Br^b 



C. tertiam partem circa longius quam latum, profunde constrictum ; sinu angusto, plerumque 



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



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



sitis. 

 2?mm.— tA"^/ = .0025". 

 Syn.— G. tetrophthalmum, (Kotzing), Be£bisson. Rabenhorst, Flora Europ. Algarum, Sect. 



IIL p. 159. 

 jjab. — New Jersey ; Wood. 

 I Ab6ut one-third longer than broad, deeply constricted ; sinus narrow, mostly snblinear ; margin 



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



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



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



17 July, 1872. 



