FRESH-WATER ALGiE OP THE UNITED STATES. 115 



8yn.—C. Venus, Kutzinq. Rabenhorsx, Flora Europ. Algarum, Sect. III. p. 134. 

 Hab. — South Carolina. (Ravenel.) 



Small, more or less slender, semicircular, eight to twelve times longer than broad, equally and 

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

 obliterated ; vesicles in each crus 3-4 ; vacuole distinct, containing 4-6 corpuscles. 



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



C. parTulum, N^o. 



C. parvum, semicirculare, medio non tumidum, gracile, anguste lanceolatum, sexies-octies lon- 

 gius quam latum, apicibus acutis ; cytiodermate tenui, Isevissimo, vacuato nonnunquam luteolo- 

 fuscescente et subtiliter striato ; vesiculis uniseriatis, in quoque crure 2-4, varius 1-T ; laminis 

 chlorophyllaceis 4-5. (R.) 



Z>iam.— Max. 0.00026"— .00062" (R.) (.0008" W.) 



Syn. — G. parvulum, N^qeli. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 134. 



Bab. — Prope 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 l-t ; 

 chlorophyllous lamina 4-5. 



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

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

 horst except in attaining a larger size. 



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



C. Jennerii, Ralfs. 



C. cylindraeeo-fusiforme, semilunare, Iseve, utrinque modice attenuatum, sexies-octies longius 

 quam latum, apicibus obtuse rotundatis ; vesiculis in quoque crure b-*l, in serie unica axili 

 dispositis; laminis chlorophyllaceis 2-3; locello subsequali magno, corpusculis numerosis 

 impleto. (R.) 



X»ta»i.— 0.00051". (R.) 



Syn. — G. Jennerii, Ralfs. Rabenhorst, 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 strise. L. ■^\^". B. jtVtt"- Archer. 

 Pritchard's Infusoria. 



b. Zygosporx plerumque quadrangulares, cellularum crura longe vel longissime producta, 



saepe setiformia. 

 b. Zygospores mostly quadrangular, crura of the cells greatly produced, often setiform. ^ 



€. rostratnm. Ehrb. 



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

 nibus setaceis singulis corpus vix sequantibas, ssepius longe brevioribus ; cytiodermate dilute 

 umbrino vel luteolo, densp striato ; vesiculis uniseriatis, in quoque crure 5-6 ; locello oblongo, 

 saepius indistincto, corpusculis 12-15 vivide se moventibus. (R.) 



