40 FRESH-WATEK, ALG^ OF THE UNITED STATES. 



C. flexuosum, (Ag.) Rabenh. 



C. strato gelatinoso, saturate viride, indefinite expanse ; trichomatibus aequalibus, pallide vel 

 saturate caeruleo-viridibus, plerumque valde flexuosis et intricatis, saepius eircinatim vel 

 fasciatim convolutis, interdum subrectis, et fasciatim eontextis; articulis oblongis, ad geni- 

 cula plus minus contractis, homogeneis vel granulatis, distinctis ; cellulis perdurantibus 

 terminalibus, subglobosis, rare hirsutis, nonnunquam in trichomatis utroque fine ; sporis 

 oblongo-cylindricis, diametro 2 — 3 plo longioribus, distincte granulatis. 



Z>iam.— Spor. y^J^/ = .000416" ; cell, veget. y,yV/ = -000166". 



Syn. — G. flexuosum, (Ag.) Rabenhobst, Flora Europ. Algarum, Sect. II. p. 188. 



Hah. — In locis irroratis, prope Philadelphia. 



Stratum gelatinous, deep green, indefinitely expanded ; filaments equal, pale or deep bluish- 

 green, mostly very flexuous and interwoven, often circinnately or fasciately convolute ; some- 

 times straightish and in bundles ; articles oblong, more or less contracted at the joints, homo- 

 geneous or granulate, distinct ; heterocysts terminal, subglobose, rarely hirsute, sometimes 

 at both ends of the filament ; spores oblong-cylindrical, 2 or 3 times longer than broad, dis- 

 tinctly granulate. 



Remarks. — The color of the filaments in young specimens is deeper than in the 

 older, which, however, grew in a much darker locality. The young spores are a 

 yellowish-green, afterwards they are of a sort of yellowish reddish-brown. In one 

 instance two spores were seen closely conjoined together at the end of a filament. 

 In some filaments one or more heterocysts occur interstitially. Often one or more 

 filaments will be seen coiled together like a rope. On the banks of the Schuyl- 

 kill Eiver I have found this species in two localities in the latter part of Sep- 

 tember. In the one instance it grew along the Reading Railroad, just above the 

 Flat Rock tunnel, in a dark little grotto, formed by shelving rocks. In the other 

 case, it was on wet ground by a horse-trough very near the west end of the upper 

 bridge at Manayunk. 



Fig. la, pi. 3, represents a filament, magnified 450 diameters. 



Fig. 1&, a portion of a filament, magnified 800 diameters. 



C. macrospermutn, Ktz. " 



C. trichomatibus curvatis vel subrectis, pallide aerugineis; articulis cylindricis vel subcylin- 

 dricis (in forma Europsea "globosis vel ellipticis"), ad genicula plus minus constrictis, 

 passim confluentibus ; cellulis terminalibus plerumque ellipticis vel ovatis, diametro paulo 

 vel subduplo longioribus; sporis elliptico-oblongis vel oblongo-cylindraceis, viridibus (in 

 formam Europseam maturam '-'saturate fuscis"), subtiliter granulosis, diametro duplo lon- 

 gioribus. 



Z)iam— Trich. cell, transv. ^^V' = .00003"; spor. .00046"— .00054". 



Syn.— C. macrospermum, Ktz. Rabenhobst, Flora Europ. Algarum, Sect. II. p. 186. 



Hah. — In rivulis, South Carolina. (Prof. Ravenel.) 



Filaments curved or straightish, pale seruginous ; articles cylindrical or subcvlindrical (in 

 European species " globose or elliptical"), more or less constricted at the joints here and 

 there confluent; terminal cells mostly elliptical or ovate, a little longer or about twice as 

 long as broad ; spores elliptical-oblong or oblong cylindrical, greenish (in mature European 

 specimens deep fuscous), finely granular, about twice as long as broad. 



Remarks.— I have received this species from Professor Ravenel, who collected 

 it near Aiken, South Carolina, in the month of September; with it was the follow- 



