FRESH-WATER ALG^ OF THE UNITED STATES. 143 



Diam.—O.OOil". Long. 0.0039". (R.) 



Syn. — M. oscitans, Ralps, British Desmidiese, p. 76. Rabenhoest, Flora Europ. Algarum, 

 Sect. III. p. 119. 

 M. pinnaiifida 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 bidentate ; end lobe short, broad, its lateral pro- 

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

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



Bemarhs. — According to Prof. 'Rahevihoxst.M. pinnatijida, Ktz., is a variety of M. 

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

 lobes narrower. 



B. Semicellulse S-vel b-lobse, plerumque radiatim inciso-lobulatae. Lobi basales assurgentes 

 aut non aut minus a loho polari remoti. 



B. Semicells 3, or 5-lobate, mostly radiately incisely lobulate. Basal lobes assurgent, either 

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



* Semicellulse trildbae. 



* Semicells trilobate. 



JH. Americana, (Ehbb.) Ktz. 



M. magna, oblonga, snbpinnatiseeta, lobis polaribus paulum remotis, psene duplo longior quam 

 lata ; cytiodermate spinuloso unde laborum margines dentato-serrati conspiciuntur ; eellula 

 e latere conspecta oblonga, in medio leviter constriota. Mtroque polo bicornuta; semicellulae 

 basi tumors plus minus distincto instructse, fere quinquelobae, lobis basales latissimi iisderaque 

 profunda bilobati, lobulis late excisis, segmentis dentato-serratis ; lobis polaribus plus minus 

 productis, in medio late excisis, segmentis profunda bifidis. (R.) 



Diam.— 0.0041". Long, circa 0.0051". (R.) 



Syn. — M. Americana, Kutzing. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 189. 



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



Frond angular elliptic, more or less punctata ; segments 3-lobed ; lateral lobes broad, cuneate, 

 tbeir margins concave, inciso-serrate ; and lobe broad, cuneate, end exserted, bipartite at the 

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



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



Hfl. Baileyi, Ralfs. 



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

 discretis, excisnra acute triangulari iri duas lacinias partitis, laciniis e basi latiori in apicem 

 truncatum bidentatum attenuatis; lobo polari e basi angnsta longe porrecto, sursum valde 

 dilatato, in vertice leviter et late sinnato, angulis truncato, bidentato. (R.) 



Syn. — M. Baileyi, Ralfs, British Desmidieas, p. 211. 



Hab. — ^NewYork; Rhode Island ; South Carolina; Florida; Bailey. 



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



M. ringens, Bailey. 



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

 laciniis divaricatis, apjee obtnsis, truncatis vel bidentatis; lobo polari e basi angusta sursum 

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



