38 PEESH-WATER ALG^ OF THE UNITED STATES. 



Filaments moiiniform, without sheaths ; spores spherical, yellow or yellowish-fuscous,, mostly sin- 

 gle, variously placed as to the heterocysts and ordinary cells. 



Bemarks. — The characters wljich I have given are somewhat different and less 

 exacting than those of Prof. Eabenhorst, otherwise our American species would 

 hardly be covered by the diagnosis. Professor Harvey in his Phycologia Britan- 

 nica states that A. Jussieu had preoccupied the name, Anabcena, by applying it to 

 a genus of Ewphorbiacece. The date of Bory's name is, however, 1823, whilst that 

 of Jussieu is 1824, Hence, it is the latter which must be changed. 



A. gelatinosa, Wood. 



A. thallo mucoso gelatinoso, indefinite expanso, dilutissime brunneo, nonnihil pellucido ; tricho- 

 matibus hand vaginatis, leviter flexubso-curvatis, nonnihil distantibus, baud intricatis, aut 

 dilute aureis aut dilute cseruleo-viridibus ; articulis globosis, homogeneis ; cellulis pevdu- 

 rantibus articulorum diametro fere sequalibus, globosis, vel rare oblongis; sporis terminalibus, 

 singulis, globosis (fusco-brunneis ?). 



Syn. — A. gelatinosa, Wood, Prodromus, Proc. Amer. Philos. Soc, 1869, 126. 



Hab. — Prope Philadelphia. 



Thallus gelatinous, mucous, indefinitely expanded, somewhat- pellucid, with- a brownish tinge; 

 filaments not vaginate, somewhat curved, rather distant, not intricate, either a light golden- 

 yellow or light bluish-green; joints globose, homogeneous; heterocysts about equal to the 

 filaments in diameter, globose or rarely oblong ; spores terminal, globose. 



BemavTcs. — The color of the shapeless mass of jelly of which the frond is com- 

 posed is a lightbrown with, in places, a decided reddish or flesh-colored tint. The 

 heterocysts are either interstitial or terminal, no hairs were detected on' them; 

 they are mostly globose and only occasionally are they oblong. 



Fig. 4, pi. 2, represents a filament of this species magnified 750 diameters; the 

 color of the endochrome of the large spore was possibly due to its being dead. 



A. flos aquas, (Ltngb.) Ktz. 



A libere natans, submembranacea, Kruginea ; trichomatibus plus minus curvatis, ssepius circi- 

 natis; articulis sphsericis vel e mutua pressione modo ellipticis modo oblongo-quadratis ; cel- 

 lulis perdarantibus ellipticis singulis vel geminis; cytioplasmate pallide serugineo granulato 

 turbato ; sporis exacte globosis aureo-fulvis lucidis, singulis interjectis, articulorum diametro 

 subduplo majoribus. R. Species mihi ignota. 



Diam.—Aviic. O.OOOIT"— 0,00025"; diam. long cell. perd. 0.00048"— 0.00053"; spor. 

 0.00032"— 0.0004". 



Syn. — A. flos aquae, (Ltngb.) Ktz. Rabenhorst, Flora Europ. Algarum, Sect. II. p. 182. 



Eab.— "Round Pond, West Point, New York." Prof Bailey. Silliman's Journal, N. S., vol. 

 iii. 18 



Swimming free, submembranaceous, reruginous; filaments more or less curved, -very often cir- 

 cinnate ; articles spherical, or, from mutual pressure, elliptical or oblong quadrate ; heterocysts 

 elliptical, single or geminate ; cytioplasm pale seruginous, granulate ; spores exactly globular, 

 golden-fulvous, bright, singly interspersed, nearly twice the diameter of the joints. 



A. ^gfantea, Wood. 



A. thallo nullo, trichomatibus singulis et numeroso-consociatis, nataotibus, rectis, in setate 

 juveni spiraliter convolutis; articulis plerumque subglobosis, arete connexis, granulosis ; eel- 



