FRESII-WATER ALG.E OP THE UNITED STATES. 115 



Syn. — C. Venus, Kutzing. Rabenhoest, Flora Europ. Algarum, Sect. III. p. 134. 



Sab. — South Carolina. (Raveael.) 



Small, more or les.s slender, semicircular, eight to twelve times longer than broad, equall}' and 

 very perceptibly attenuate at both apices; cytioderm thin, smooth; chloropliyllous lamina 

 obliterated; vesicles in each crus 3-4; vacuole distinct, containing 4-C corpuscles. 



Remark. — Fig. 7, pi. 11, represents in outline a frond magnified 450 diameters. 



C. parTiiliim, N^g. 



C. parvuin, seniicireulare, medio non tumidum, gracile, angu.ste lanccolatura, sexies-octies lon- 

 gius quam latum, apicibus acutis; cytiodcrniate tentii, lievLssinio, vacnato nonnunquam luteolo- 

 fuscescente et subtiliter striato; vesiculis uuiseriatis, in quoque crure 2-4, varius 1-7 ; lamiuis 

 chlorophyllaceis 4-5. (R.) 



Z»iam.— Max. 0.0002C"— .00062" (R.) (.0008" W.) 



Syn. — C. parvulum, N^geli. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 134. 



Bah. — Frope Philadelphia, Wood. 



Small, semicircular, not swollen in the middle, slender, narrowly lanceolate, six to eight times 

 longer than broad, with the apices acute; cytioderm thin, very smooth, when empty some- 

 what yellowish-fuscous and finely striate; vesicles uniseriate, in each crus 2-4, rarely I-T; 

 chloroi)hyllous lamina 4-5. 



Bemarhs. — I have referred to this species a desmid which T have found about 

 Philadelphia, and which agrees in all respects with the description of Prof. Itaben- 

 horst except in attaining a larger size. 



Fig. 5, pi. 12, represents this plant magnified 450 diameters. 



C. Jennerii, Ralps. 



C. cylindraceo-fusiforme, serailunare, teve, utrinque modiee attenuatum, sexies-octies longius 

 quara latum, apicibus obtuse rotnndatis; vesiculis in quoque crure 5-7, in serie unica axili 

 dispositis; lamiuis chlorophyllaceis 2-3; locelio subaquali magno, corpusculis numerosis 

 impleto. (R.) 



Z)m7«._0.00057". (R.) 



Syn. — C. Jennerii, Ralfs. Rabendorst, Flora Europ. Algarum, Sect. III. p. 134. 



Hah. — Rhode Island, Bailey. 



Frond small, distance between the extremities six or seven times the breadth, crescent-shaped, 

 much curved, gradually tapering (sometimes with an obscure central constriction); upper 

 margin very convex, lower very concave without a central inflation ; ends obtuse, rounded ; 

 large granules in a single series; e. f. colorless without striae. L. ^J/'. R- 1735"- Archer. 

 Pritchard's Infusoria. 



b. Zygospores plerumque quadrangulares, cellularum crura longc vel longissime producla, 



saepe setiformia. 

 h. Zygospiores mostly quadrangular, crura of the cells greatly produced, often sctiform. 



C rostratiini. Ehrb. 



C. corpore lanceolato-fusiformi, utrinque valde et longe attenuato, leviter curvato, striato ; cor- 

 nibus setaceis singulis corpus vis £e(|uantibus, saepius longe brevioribus ; cytiodermate dilute 

 umbrino vel luteolo, dense striato : vesiculis uniseriatis, in quocpie erure 5-0; locelio oblongo, 

 ssepius indistincto, corpusculis 12-15 vivide se moveutibus. (R.) 



