FRESH-WATER ALG^ OP THE UNITED STATES. 143 



Z)ta?n.— 0.0047". Long. 0.0039". (R.) 



Syn. — M. oscitans, Ralfs, British Desmidiese, p. 76. Rabenhorst, Flora Europ. Algarum, 

 Sect. III. p. 119. 

 M. pinnalifida Ktz. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 119. 



Eah. — Florida; Rhode Island; Bailey. 



Frond about as broad as long, pinnatifid; lateral lobes separated from the terminal by a rounded 

 sinus, horizontal, conical, their extremities bideatate ; end lobe short, broad, its lateral pro- 

 jections short, conical, usually bidentate, narrower and shorter than the lateral lobes ; ends 

 convex at the centre; tr. v. fusiform, e. f. punctate. (A.) 



Remarhs. — According to Prof. Rabenhorst M. j){nnatifida, Ktz., is a variety of M. 

 oscitans, different from the typical form only in being smaller, and in having the 

 lobes narrower. 



B. Semicellulas 3-vel b-lohx, pleruvique radiatim inciso-lobulatse. Lobi basales assurgentes 

 aut non aut minus a lobo polari remoli. 



B. Semicells 3, or b-lohate, mostly radiately incisely lobulate. Basal lobes assurgent, either 

 close to, or but slightly remote from the end lobes. 



* Semicellulae trilobx. 



' * Semicells trilobate. 



HI. Americana, (Ehrb.) Ktz. 



M. magna, oblonga, subpinnatiseeta, lobis polaribus paulum remotis, paene duplo longior quam 

 lata; eytiodermate spiuuloso unde laborum margiues dentato-serrati couspiciuiitur ; collula 

 e latere conspecta oblonga, in medio leviter constricta. utroque polo bicoruuta; semicelluliB 

 basi tumoreplus minus distincto instructae, fere quinquelobfe, lobis basales lati.ssimi ii.-^deiiique 

 profunde bilobati, lobulis late e.xcisis, scgmentis dentato-serratis; lubis polaribus plus minus 

 productis, in medio late cxcisis, segmentis profunde bifidis. (R.) 



Diam.—Q.WiV. Long, circa 0.0051". (R.) 



Sifn. — M. Americana, KiJTZi.VG. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 189. 



Hab. — In stagnis. South Carolina; Florida; Bailey. 



Frond angular elliptic, more or less punctate; segments o-lobed ; lateral lobes broad, cuneate, 

 their margins concave, inciso-serrate ; and lobe broad, cuueate, end exserted, bipartite at the 

 angles, the subdivisions narrow, and minutely dentate at the extremities ; end concave. (A.) 



RemarTc. — Fig. 17, pi. 12, represents a plate of this species. 



M. Baileyi, Ralfs. 



M. parva, oblonga, granulata ; semicellulis trilobis, lobis basalibus a lobo polari sinn amplo 

 discretis, excisura acute triangular! ill duas lacinias partitis, laciniis e basi latiori in apicem 

 truncatum bidentatura attenuatis; lobo polari e basi angusta longe porrecto, sursum valde 

 dilatato, in vertice leviter et late sinuato, angulis truncate, bidentato. (R.) 



Syn. — 31. Baileyi, Ralfs, British Desraidieoe, p. 211. 



Hab. — New York; Rhode Island ; South Carolina; Florida; Bailey. 



Frond granulated ; segments three-lobed ; lobes bipartite, end one much exserted. (Ralfs.) 



M. ringens, Bailey. 



M. niediocris, oblonga, margine granulata; semicellulis trilobis; lobis lateralibus bipartitis, 

 laciniis divaricatis, apjce obtusis, truncatis vel bidentatis; lobo polari e basi angusta sursum 

 valde dilatato, exserto, in vertice leniter sinuato, angulis truncato. (R.) 



