FRESn-WATEll A L G .E OF TUE U ^■ 1 T E D STATES. 47 



Cr. angulosa, (Roth.) J. Aqh. 



G. globoso-angulosa, cava, viridi-fuscescens, ad cerasi magnitudinem ; trichomatibus strictis, 

 torulosis, supenie leviter flexuosis, passim interruptis ; articulis inferioribus plus minus 

 corapressis, diaraetro duplo triplove longioribus ; vaginis amplis, achrois hie illic leviter con- 

 strictis; sporis plus minus elongatis, oblongo-ovatis vel ellipsoideo-cylindricis, diametro 3-fi- 

 10 plo longioribus, ajrugineo-fuscescentibus, noununquam leviter curvatis, cytioplasmate sub- 

 tillter granuloso, turbato. (R.) Species mihi ignota. 



Diam.—CtW. perd. 0.00036"— 0.0005". Spor. ma.x. 0.00059". (R.) 



Syn. — O. angulosa, (Rotii.), J. Agardh., Rabenuorst, Flora Europ. Algarum, Sect. II. p. 201. 



Hab. — Hudson River props West Point. (Bailey.) 



Globose angular, hollow, greenish-fuscous, attaining the size of a cherry ; filaments strict, toru- 

 lose, above somewhat flexuose, here and there interrupted; inferior joints more or less com- 

 pressed, 2-3 times longer than their diameter; sheath ample, colorless, here and there slightly 

 constricted; spores more or less elongate, oblong-ovate or ellipsoidal-cylindrical, 3-6-10 

 times longer than the diameter, airuginous-fuscous, sometimes slightly curved, cytioplasm 

 very minutely granulate. 



Genus RIVULARIA, (Roth.) Agh. 



Thallus et trichomata cadem quae Gloiotricha, sed vagina: arctissimaj, sape in gelatinam matri- 

 calem confluentes, quasi nullae. 



Thallus and filaments similar to those of Gloiotricha, but the sheaths very close, often confluent 

 in the gelatinous matrix and apparently wanting. 



Remarks. — The characters given above are those of Professor Rabenhorst. 

 Flora Europ. Algarum, Sect. II. p. 206 



R. cartilag^inea, Wood. 



R. subglobosa, parva, cartilaginea, saturate brunnea vel subatra, solitaria in plantis aquaticis: — 

 trichomatibus maturis-sterilibus, rectis aut subrectis, cylindricis, elongatis, baud articnlatis ; 

 cytioplasmate siEpe interrupto; vaginis arctis et distinctis; cellulis perdurantibus globosis, 

 diametro subsqualibus : — trichomatibus fertilibus — rectis aut subrectis, supra spora cellulis 8-9 

 instructis; sporis elongatis, rectis, cylindricis; vaginis nonnihil crassis, arctis: — trichomatibus 

 immaturis breve articulatis; vaginis subamplis. 



i>ifflm.— Trieh. cum vag. ^^V??" ; spor ,^V/- 



Syn. — R cartilaginea, Wood, Proc. Am. Philos. Soc, 1869, p. 128. 



Hah. — In palude. Northern Michigan. 



Frond subglobose, small, cartilaginous, deep brown or blackish, solitary upon aquatic plants; 

 mature sterile filaments, cylindrical, elongated, not articulated, their cytioplasm frequently 

 interrupted, their sheaths close and distinct, their heterocysts globose and about equal to 

 them in diameter; fertile filaments straight or nearly so, above the spores furnished with 8 or 

 9 cells ; spores elongate, straight, cylindrical ; sheaths rather thick, close ; immature filaments 

 shortly articulate, their sheaths rather large. 



Remarlcs. — The frgnd of this species grows attached to the leaves of water-plants, 

 and has its under side markedly flattened so that it is somewhat semi-globose. The 

 filaments which compose the mass of the very firm frond arc elongated, cylindrical, 

 and of nearly or entirely uniform diameter throughout. The sheaths are close, 

 distinct, rather thin, open above, and, in many instances, almost or even entirely 

 empty. Scattered amongst such filaments are the fertile ones. These have at 

 theit base an elongated cell, in which is the long cylindrical spore, which varies 



