FRESH-WATER ALG^ OF THE UNITED STATES. HI 



2. Cells cylindrical, with the dorsum more or less convex, the belli/ straightish, 7iever ventri- 

 cosely inflated. 



C lilinilla, (MiJLLEK) Ehrb. 



C. permagrium, sublseve ^striae subtilissimse vel indistinctae), semilunare, dorso alte convesum, 

 ventre subplanura, apicibus attenuatis rotundatis ; vesiculis chlorophyllaceis numerosis spar- 

 sis; locello distiucto subapicali eorpuscula uuraerosa includente. (R.) 



Z»ia?7i.— jV'— jV" = 0- 00032"— 0.0045". (R.) 



Syn. — G. Lunula, (Muller,) Ehrb. Rabenoorst, Flora Europ. Algaruni, Sect. III. p. 127. 



Bob. — South Carolina, Georgia, Florida. Prof. Bailey. Pennsylvania. Wood. 



Very large, smoothish (striae very fine or indistinct), semilunar, dorsum strongly convex, belly 

 straightish, the ends attenuate and rounded; chloropliyl globules numerous, scattered; vesi- 

 cle distinct, subapical, including numerous corpuscles. 



C acerosuin, (Scurank) Ehrb. 

 ( Var. nov. maxiniuiii.) 



C. lineare-fusiforme, sub-rectum aut leve curvatum, ntroque fine sensim et paullulum atten- 

 uatuui, diametro 16-24 plo longiore; apicibus angustissime truncatis, achrois; meml)raiia 

 hand striata; vesiculis chlorophyllaceis 11-14 in quoque crure, in serie axilli simplici collo- 

 catis; locello apicali parvo, eorpuscula uumerosa includente; zygosporis globosis. 



J»ia?n.— Transv. max. -^11-^" =■■ .OOlt" ; zygosp. ^H^" = .0027". 



Syn. — C. acerosum, (Schrank) Ehrb. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 

 128. 



Hah. — Pennsylvania; Wood. South Carolina, Georgia, Florida; Bailey. 



Linear, fusiform, straightish, or slightly curved, at each end sensibly little by little attenuate, 

 15-24 times longer than broad; apices narrowly truncate, transparent; membrane not striate; 

 chlorophyl globules 11-14 in each limb placed in a simple axillary series; apical vesicle 

 small, containing numerous corpuscles ; zygospores globose. 



Remarhs. — The desmid, described above, was found in New Jersey, near Cam- 

 den. It differs from the typical form of C. acerosum in its size, proportionate 

 len<Tth to breadth, -and in not being striate. The European '■'■ forma major" 

 (Rabenh.) appears, however, to exxeed it in transverse diameter, and, according 

 to some authors, certain fronds of the species are not striate, and all authorities 

 agree that at times the striae are exceedingly delicate. For these reasons, I think, 

 our American form must be regarded simply as a variety. As far as can be judged 

 from the rude figure, it is this species which Prof Bailey identifies as C. ienue, 

 Ktz., in Silliman's Journal for 1841. 



Fig. 5, and 5 a, pi. 11, represent this species magnified 250 diameters; 5 b 

 represents the sporangium with portions of the dead fertile fronds still attached. 



C. areolatiiui, Wood, (sp. nov.) 



C. fuslforme, subrectum vel notfnihil curvatum, lateris ventralis medio ssepe paullulum concavum, 

 diametro 9-10 plo longius, utrinque niodice attenuatum; apicibus truncato-rotundatis ; mem- 

 brana crassa, et firma, rubido-brunnea, profunde distante striata, et minutissime sed distincte 

 granulata vel areolata; suturis medianis distinctissimis 4-10. 



Diam. — 0.0024". 



Hob. — In aquis puris quietis ; Northumberland Co., Pennsylvania. 



