40 



FRESH-WATER AhGM OF THE UNITED STATES. 



C. flCXIIOSIIIM, (AG.) Rabenh. 



C. strato gelatiiioso, saturate viride, indeBnite expanse ; trichomatibus sequalibas, pallida vel 

 saturate ca>ruleo-vindibus, plcrunique valde flexuosis et intricatis, sa?pius eircinatim vel 

 fasciatim coiivulutis, inturdum subrectis, et fasciatim coutcstis; articuiis oblongis, ad geni- 

 cula plus minus coutractis, homogeneis vel granulatis, distinctis ; cellulis perduraiitibus 

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

 oblongo-cylindricis, diainetro 2 — 3 plo longioribus, distinutc granulatis. 



Diam—Spor. ^5^5/ == -000416" ; cell, veget. ^Au" = .000166". 



Srjn. — C. flcxuosum, (Ag.) Rabenhorst, Flora Europ. Algarum, Sect. II. p. 188. 



Ilab. — In locis irroratis, propo Philadelphia. 



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

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

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

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

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

 tinctly granulate. 



Remarlcs. — The color of the filaments in yovmg 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 River 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. 1Z», a portion of a filament, magnified 800 diameters. 



C. macrosperniuni, Ktz. 



C. trichomatibus curvatis vel subredtis, pallide ajrugineis; articuiis cylindricis vel subcylin- 

 dricis (in forma Europcea " 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 Europaeam maturam '•' saturate fuscis"), subtiliter granulosis, diametro duplo lon- 

 gioribus. 



Z>«a»i— Trich. cell, transv. ^^V/ = -OOOOS" ; spor. .00046"— .00054". 



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



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



Filaments curved or straightish, pale sernginous ; articles cylindrical or subcylindrical (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. 



Eemar7cs.—1 have received this species from Professor Ravenel, who collected 

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



