FRESH-WATER A L G .E OF THE UNITED STATES. 133 



angulis rotundatis, dorso truncato-rotundatis, margine crenulato-dentatis, a dorso oblongis, 

 medio veutricosis, utroque polo plus minus tumidis ; cyliodermate graimlato margaritiferu. 

 (R.) 



Long. 0.0010"— 0.0012." Lat. 0.0013"— 0.0015". (R.) 



Si/n. — C. commissurale, Bueblsson. Rabeniiorst, Flora Europ. Algarum, Sect. III. j). 170. 



Hab — In lacu. White Mountain.'?, New Hampshire ; (Dr. P. W. Lewis) 



Frond small, in f. v. one-third broader than long; constriction very deep, rounded ; segments 

 narrow-reuiform, with a central, somewhat truncate projection, produced by the continuation 

 of the central inflation, rough on the inflation and on the extremities, with somewhat large 

 pearly granules, e. v. three times longer than broad, constricted between the central inflation 

 and the rounded extremities. Sporangium as in 6'. ornalum. (A.) 



Remarks. — I have seen but a single specimen of this species which differed from 

 the typical form, in having tlie sinus very narrow in its outer portion, and in being 

 shorter. 



Fig. 16, pi. 13, represents the frond of this specimen, magnified 750 diameters. 



C caelatiiiii, Ralfs. 



C. suborbiculare, profunde constrictum ; sinu angustissimo linear! ; semicellulis inciso-crenatis, 

 angulis rotundatis, a vertice medio nonnihil inflatis; cyliodermate granulato, granulis in 

 series regulariter cireulares positis. 



Z»mm.— Long. -^^^V' = -00 U". Lat. t^Vstj" = -0014". 



Syn. — C. caelalum, Ralfs, British Desmidieie, p. 103. 



Hab. — In stagnis prope Aiken, South Carolina. (Ravenel.) 



Suborbicular, profoundly constricted; sinus very narrow, linear; seraicells inciso-crenate, 

 angles rounded, when seen from the end somewhat inflated in the middle ; cytioderm granu- 

 late, granules placed in circular series. 



Remarks. — This species was collected by Prof Ravenel in a quiet ditch near 

 Aiken, South Carolina, sparsely scattered amidst innumerable diatoms and desmids. 

 The number of the crenations appears to vary. In the few individuals I have seen 

 there were six end ones besides the two very broad basal ones, if the latter can be 

 called crenatures. Ilalfs gives six as the total number,, and yet every one of his 

 figures has many more. So I think the number a character of but little import- 

 ance. The circular arrangement of the granules is not so positive and regular in 

 the specimens I have seen, as is represented in the figure of llalfs, otherwise the 

 agreement is perfect. 



C. Brooinei, Thwaites. 



C. subparvuni, plcrumque tam longum quam latum, nonnunquara paulo longius, obtuse quad- 

 rangulare, profunde constrictum, sinu angustissimo lineari ; semicellulis oblongo-quadrangulls, 

 diametro duplo longioribus, angulis et inferioribus et superioribus ol)tuse rotundatis, ventre 

 subplanis, dorso latissime truncatis et saepius leniter retusis vel plane convexis; cytioder- 

 mate granulato-margaritaceo, granulis in seriebus subrectis collocatis. (R.) 



Long, 0.00194"— 0.0022". Lat. max. .002", thick .0015". 



Syn. — C. Broomei, Thwaites. Ralfs, British Desmidie*, p. 103. 



Eab. — Georgia; Bailey. Prope Philadelphia ; Wood. 



