128 FRESH-WATER ALG^E OF THE UNITED STATES. 



a very broad neck. I have never seen the sporangia, but, according to Mr. Ralfs, 

 they are orbicular and inclosed in a granulated cell. 



Fig. 8, pi. 21 , represents half of an empty frond of this species magnified 750 

 diameters; and fig. 21, pi. xii., a frond densely filled with living endochrome 



C. Botrytis, (BORY) MENGH. 



C. late ovale, profunde constrictum, diametro plerumque l 2 plo longius ; sinu angusto, 

 lineare ; semicellulis nonnihil triangularibus, apice iiiterdum truncatis, interdimi late rotun- 

 datis ; cytiodermate minute granulate. 



Diam. 5 ^ ff " = 0.0019" (0.0014" 0.0023"). (R.) 



Syn. C. Botrytis, (BORY) MENEGHENI. RABENHORST, Flora Europ. Algarum, Sect. III. p. 

 158. 



ITab. Pennsylvania, Wood. 



C. broadly oval, profoundly constricted, l-2 times longer than broad; sinus narrow, linear; 

 semicells somewhat triangular, with the apex sometimes truncate, sometimes broadly rounded ; 

 cytioderm minutely granulate. 



Remarks. In this species the semicells, as viewed transversely, are broadly 

 elliptic in outline. The end view presents a longer narrower ellipse. Their out- 

 line, when seen from the front, varies remarkably from that of a very broad semi- 

 oval to distinctly triangular with a truncate apex. The granules are small and 

 arranged regularly, sometimes they are very obscure. I have often seen the endo- 

 chrome so arranged as to leave a large pyriform central vacuole in each cell, com- 

 municating with the narrow margin between it and the cell-wall. This vacuole 

 was apparently filled with a transparent fluid, in which were minute granules in 

 immense numbers, in constant active motion circling among one another and pass- 

 ing out, into and along the marginal connecting space. According to Ralfs, the 

 sporangia of this species are large (jj^")> with branched spines. 



Fig. 5, pi. 21, represents an empty frond of this species; 5 a, outlines of semi- 

 cells to show the variations, and fig. 14, pi. 12, represents a frond crowded with 

 endochrome, magnified 460 diameters. 



C. ovale, RALFS. 



C. magnum, ovale, compressum, profunde constrictum, diametro subduplo longius, ambitu inte- 

 gerrimum vel crenatum, a vertice late ellipticum ; semicellulis basi paulo latioribus quam 

 longis, triangulo-rotundatis, disco punctatis, margiue verrucis margaritaceis achrois hyalinis 

 in series 4 ordinatis. (R.) 



Diam. Long. 0.0053" 0.0067". Lat. plerumque 0.0041". (R.) 



Syn. C. ovale, RALFS, British Desmidiese, p. 98. 



Bab. South Carolina ; Rhode Island ; Bailey. Cobble Mountain, Pa. (Lewis) Wood. 



Frond very large, elliptic, nearly twice as long as broad, constriction very deep, linear; seg- 

 ments somewhat broader than long, somewhat triangular, rounded at ends, rough near the 

 margin, with a band of large pearly granules, producing a dentate appearance, the disc punc- 

 tate; e. v. elliptic. (A.) 



C. Br6bissonii, MENEOH. 



C. paulo longius quam latum ; semicellulis semicircularibus, diametro paulo longioribus, angulis 

 inferioribus obtusis approximatis, ventre modice concavis subplanis, dorso latissime rotun- 

 datis; cytiodermate muricato, muricibus conicis in ordinibus regularibus collocatis. (R.) 



