FRESH-WATER ALG^ OF THE UNITED STATES. 113 



of them, however, are a little more curved in the central portion than it would 

 imply. 



Fig. 1, pi. 12, is a drawing of an American plant, magnified 160 diameters. 



C Cucumis, Ehrb. 



C. oblongum, turgidum, leviter curvum, Iseve, diametro 4-T plo longius, apicibus obtusis. (R.) 



Syn. — C. Cucumis, Ehrenberq, Verbreit. b. 28, IV. F. 28. Rabenhoest, Flora Europ. Algar 

 rum, Sect. III. p. 138. 



Hub. — New York ; Ehrenberg. 



Oblong, turgid, slightly curved, smooth, 4-T times longer than broad, the apex obtuse. 



Eemarks. — I have no knowledge of this species other than that in the above 

 short description, which has been copied frohi Rabenhorst's works. 



3. Cellulae semilunares, plerumque magis curvatse quam in Sect. 1 et 2, ventre semper tumidx, 

 ventricoso-injlatse. 



3. Cells semilunar, mostly more curved than in Sect. 1 and 2, with the belly always tumid, 

 ventricosely injlated. 



C. Ehrenbergii, Mengh. 



C. fusoideo-semilunare, ventre inflato, ceterum ut in C. Lunula. (R.) 

 Z>mm.— Lat. j^§/ = .0029". Long, ^f^/ = .0042." 



Syn. — C. Ehrenbergii, Menqs. Rabenhoest, Flora Europ. Sect. III. p. 131. 

 Hab. — Prope Philadelphia. 



" Frond large, stout, about five or six times as long as broad, Innately curved, extremities taper- 

 ing; upper margin very convex, lower concave with a conspicuous central inflation; ends 

 broadly rounded ; large granules, numerous, scattered ; fillets several ; e. f. colorless, without 

 striae, central suture not evident. Sporangia orbicular, smooth, placed between the but- 

 slightly-cotinected empty conjugated fronds, the endochrome during the process of conjuga- 

 tion emerging from the opened apex of a short conical extension from each under side of each 

 younger segment (or shorter cone) of each pair of recently divided fronds, the conjugating 

 fronds being produced immediately previously by the self-division of a pair of old fronds — two 

 sporangia being thus the ultimate produce of the two original fronds. L. 5*5"; B. ^^". 

 Archer." Pritchard's Infusoria, p. 748. 



Semark.—Fig. 2, pi. 12, represents a plant of this species magnified 160 dia- 

 meters. 



C. monilifernm, (Bobt) Ehbb. 



C. semilunare, plus minus curvatum, diametro maximo 6-9 plo longius, ventre inflato, utroque 

 polo sensim attenuatum, apicibus achrois obtusis, vesiculis chlorophyllaceis in serie unica 

 longitudinali axili dispositis, in quoque crure 7-10; locello apicali submagno, corpuscula 

 numerosa includente (corpusculum in quoque locello unicum mobile ellipsoideum, magnitudine 

 lineae partem millesimam sequans, cetera mobilia per totum corporis distributa observavit cl. 

 Perty.) (R.) Species mihi ignota. 



i?iam.— 0.0019"— 0.0022". (R.) 



Syn. — C. moniliferum, Rabenhoest, Flora Europ. Algarum, Sect. III. p. 131. 



Hab. — Georgia ; Rhode Island ; Bailey. 

 15 June, 1872. 



