Wood.] ^'^^ [June 18, 



C. MINUTUM. Sp. Nov. 



C. trichomatibus dilute aeragineis, plerumque flexuoso-curvatis et 

 intricatis, interdum subrectis; articulis cylindricis, ad genicula plus 

 minus constrictis, liomogeneis vel graiiulatis ; cellulis perdurantibus ter- 

 minalibus, hirsutis, globosis ; sporis ellipticis, diametro 2-3 plo longiori- 

 bus, subtilissime granulatis. 



Filaments light aeruginous green, generally curved and intricate, 

 sometimes straiglitish ; articles cylindrical, more or less constricted at 

 the joints, homogeneous or granulate ; heterocysts terminal, hirsute, 

 globose ; spores elliptical, 3-3 times longer than broad, very minutely 

 granulate. 



Diam. Artie. 9^00" ; spor- long- leW I transv. ^oW- 



Hab. In stagnis prope Philadelphia. 



GKN. ANABAENA. 



A. GELATINOSA. Sp. NoV. 



A. thallo mucoso gelatinoso, indefinite exj^anso, dilutissime brunneo, 

 nonnihil pellucido ; trichomatibus hand vaginatis, leviter flexuoso-curva- 

 tis, nonnihil distantibus, baud intricatis, aut dilute aureis aut dilute 

 caeruleo-viridibus ; articulis globosis, homogeneis ; cellulis perduranti- 

 bus articulorum diametro fere aequalibus, globosis, vel rare oblongis ; 

 sporis terminalibus, singulis, globosis, (fusco-brunneis ?) 



Thallus gelatinous, mucous, indefinitely expanded, somewhat pel- 

 lucid, 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 fila- 

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



Hab. Prope Philadelphia. 



GEN. NOSTOCHOPSIS. Oen. Nov. 



Trichomata ramosa cum cellulis perdurantibus aut in latere sessilibus 

 aut in ramulorum brevissimorum apicibus dispositis. Vaginae nullae. 

 Thallus definitus. 



Thallus definite ; filament branched ; heterocysts sessile upon the sides 

 of the filaments or raised upon the apices of short branches ; sheaths 

 none. 



Bemarks. — The curious plant upon which this genus is founded has 

 the habit of a nostoc. The outer portion of the frond is condensed so 

 as to give the appearance of a periderm ; there is, however, no true peri- 

 derm. The consistence of the thallus is that of a firm gelatinous mass. 

 The trichomata or filaments radiate from the inner part of the frond 

 towards the outer surface, but many of them take their origin in the 

 outer portions of the thallus. In most places they are distinctly articu- 

 lated, and indeed often seem to be composed of globular cells, resem- 

 bling the filaments of a nostoc ; on the other hand in certain portions 

 they are not at all articulated. No sheaths are anywhere visible. The 

 heterocysts are strangely enough never placed in the continuity of the 



