FRESH-WATER ALG^ OP THE UNITED STATES. Ill 



2. Cells cylindrical, with the dorsum more or less convex, the belly straightish, never ventri- 

 cosely inflated. 



C. liUnula, (MiJLLEE) Ehrb. 



C. permagnum, sublaeve (stfm subtilissimee vel indistinctsB), semilunare, dorso alte convexum, 

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

 sis; locello distincto subapicali corpuscula numerosa includente. (R.) 



Diam.—:sV—^V = 0. 00032"— 0.0045". (R.) 



Syn.—G.Lunula, (Mtjllee,) Ehrb. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 12t. 



Eab. — 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 ; chlorophyl globules numerous, scattered ; vesi- 

 cle distinct, subapical, including numerous corpuscles. 



C acerosnm, (Schbank) Ehrb. 

 ( Far. nov. maximum.) 



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

 uatum, diametro 16-24 plo longiore; apicibus angustissirae truncatis, achrois; membrana 

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

 catis; locello apicali parvo, corpuscula numerosa includente; zygosporis globosis. 



Z)m?n.— Transv. max. ^Jf/ = -0011" ; zygosp. ^Ifj" =.0027". 



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

 128. 



Hab. — 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 G. acerosum in its size, proportionate 

 length to breadth, and in not being striate. The European '•'■formd major" 

 (B-ABEDiTH.) appears, however, to exceed 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 G. tenue, 

 Ktz., in Silliman's Journal for 1841. 



Fig. 5, and 5 a, pi. 11, represent this species magnified 260 diameters; 5 h 

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



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



I C. fusiforme, subrectum vel nontiihil curvatum, lateris ventralis medio ssepe paullulum concavum, 



diametro 9-1 plo longius, utrinque modice 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. 



JXam.— 0.0024". 



Eab.— In aquis puris quietis; Northumberland Co., Pennsylvan'ia. 



