132 FRESH-WATER ALG^ OF THE UNITED STATES. 



C. undulatum, Corda. 



C. subraediocre, oblongum, diametro subdupio longius, utroque polo late rotuudatum, ambitu 

 leviter sinuato-undulatum, profunde constrictum, siiiu linear! extrorsum paullum ampliato ; 

 semicellulis semiorbicularibus, et dorse et lateribns late rotundatis, margine undulato-crenatis, 

 crenis 9, sublatis ; cytiodermate Isevi ; zygosporis sphsericis spinis elongatis, apice bi- tri-fidis 

 obsitis. (R.) Species mihi ignota. 



Long. 0.0024". Lat. 0.0017". (R.) 



Syn. — C. undulatum, Corda. Rabenhorst, Flora Europ. Algarura, Sect. III. p. 165. 



Hah. — South Carolina ; Rhode Island ; Bailey. 



Frond rather larger than that of G. crenatum, slightly longer than broad, constrictions linear ; 

 segments semiorbicular, ends and sides broadly rounded, crenate or minutely undulate at the 

 margin ; e. v. elliptic. Sporangium orbicular, spinous ; spines elongate, slender, swollen at 

 the base and divided at the apex. (A.) 



6. Semicellulae medio-ventricoso inflatse. 



b. Semicells medianly ventricose. 



* Cytiodermate Isevi. 



* Gytioderm smooth. 



C sublobatum, (Breb.) Archer. 



C. parvum, oblongo subqnadratum, diametro subdupio longius, sinu angusto lineari ; semicel- 

 lulis subquadratis, e basi dilatata ad verticem sensim angustatis, angalis et inferioribus et 

 superiovibus rotundatis, dorso late truncatis lateribusque leviter sinuatis ; cytiodermate 

 Ifevissimo. (R.) 



Long. 0.00179"— 0.00196". Lat. max. 0.0015"— 0.00157". (R.) 



Syn. — C. sublobatum, (Br£bisson) Archer. Pritchard's Infusoria, p. 731. 



Sab. — Georgia; Florida; Rhode Island ; Bailey. 



Frond scarcely twice as long as broad, oblong ; constriction linear, segments subquadrate, 

 somewhat wider at the base, lateral and end margins slightly concave, smooth and trans- 

 verse vein cruciform. (A.) 



* * Cytiodermate granulate. 



* * Cytioderm granulate. 



C. ornatum, Ralfs. 



C. parvum, plerumque tam longum quam latum; semicellulis reniformibus, diametro duplo 

 longioribus, angnlis inferioribus una cum lateribus rotundatis ; dorso sub-produeto late trun- 

 catis; cytiodermate granulato-verruculoso ; zygosporis longe spinosis, spinis elongatis apice 

 fnrcatis. (R.) Species mihi ignota. 



Long. 0.0016"— 0.0015". Lat. 0.0016". (R.) 



Syn. — G. ornatum, Ralps, British Desmidiese, p. 104. 



Hab.— Rhode Island ; (S. T. Olney) Thwaites. 



Frond in f. v. about as long as broad, constriction deep, linear ; segments semiorbicular or 

 subreniform, with a central truncate projection at the ends produced by the continuation of a 

 central inflation, rough towards the margin and on the inflation with pearly granules ; e. v. 

 with a rounded lobe on each side. Sporangium orbicular, spinous ; spines elongated, dilated 

 at the base and slightly divided at the extremity, ^^^". (Archer.) 



C commissurale, (Br£b.) 



C. minutum, fere dimidio latins quam longum, profundissime constrictum, sinu amplo basi ex- 

 cavate ; semicellulis. anguste reniformibus, diametro paene triple longioribus, leviter incnrvis, 



