FRESH-WATER ALGiE OF THE UNITED STATES. 51 



Frond small, about the size of a small pea, irregularly subglobose, soft, gelatinous, light green, 

 filaments generally slraightisli, partly distinctly, partly indistinctly articulate ; sheaths in the 

 mature filament not perceptible ; in the young filaments rather large in the upper portion ; 

 heterocysts subglobose or globose or elliptic, twice as large as the filament, generally single 

 but sometimes bi or tri-seriale. 



Remarks. — I found this species growing attached to the little leaves of various 

 minute cryptogamic and phanceroganiic water-plants, in a small bog, near the 

 mouth of Carp River, in Northern Micliigan. The frond is somewhat translucent, 

 with a slightly greenish tint, and lias a soft, gelatinous consistency. The matured 

 trichoma or lilaments are more or less radiating, very long, generally nearly straight 

 and parallel. Their joints or articles are long, mostly not very distinctly separated, 

 and often are entirely wanting. The sheaths are entirely lost, no traces of them 

 being perceptible. They seem to be altogether melted down into tlie homoge- 

 neous jelly, in which the filaments are imbedded. The basal cell is hirge, mostly 

 globular, and very prominent. On the edges of the frond may frequently be seen 

 small, evidently immature filaments, which have no distinct basal cell. Around 

 the basal portion of these young trichoma there is a well-marked close slieath, 

 which near the apex is wanting. In tlieir immature filaments the joints are mostly 

 very short, rather distinctly separated, almost globular. 



Fig. 5, pi. 4. 



Genus MASTIGOXEMA, Schwabe. 



Trichoraata articulata, sursum flagelliforraia vel subulata, simplicia vel pseudornmosa (nonnunquam 

 fasciculatim pseudoramosa), procunibentia vel crecta, in thallo indistineto csspitoso-aggregata; 

 vagince arctse et homogeueaj vel auiplaj et phis minus dislincte lamellosai, apiee plerumque apertse, 

 interdum laciniataj. 



Filaments articulate, superiorly flagellifomi or subulate, simple, or falsely branched, sometimes 

 faseieulately so, procumbent or erect, csspitosely aggregated into a sort of thallus ; sheaths close 

 and homogeneous or ample, and more or less distinctly lamellate, the apex for the most part open, 

 sometimes laciniate. 



M. fertile, Wood, (sp. nov.) 



M. ccespitosum, cum algis alteris intcrmixtum; triehomatibns simplicibns, clongatis, flexuoso- 

 eurvatis, apice truncatis; trichomatibus interiiis viridibus, sa'iie iuterruptis, interdum dis- 

 tincte articulatis interdum inarticulatis; articulis diametro 3-5 plo longioribus; vaginis modice 

 arctis, firmis, achrois, crassis, colons expertibus, apice truncatis et apertis ; sporis cylindricis, 

 sparsis, in filainento unico s»pe pluribus, in cellulis inclusis; ccllulis perduraiitibus globosis, 

 interdum conipressis trichomatis diametro fere a;qualibus. 



Diam.— Filam. ^^'5/ ^ .00033" ; spor. ^^V/ = .00016G". 



Hah. — In stagnis. Alleghany Mountains, Centre County, Pennsylvania. 



Cffispitose, intermixed with other algaj ; filaments simple, elongate, flexuously curved, trun- 

 cate at the apex ; internal filament green, often interrupted, sometimes articulated, some- 

 times not articulate ; joints 2-3 times longer than their diameter ; sheath moderately close, 

 thick, firm, transparent, and colorless, truncate and open at the apex ; spores cylindrical, 

 scattered, each contained in a cell, frequently several in a filament; heterocysts globose, 

 sometimes compressed, about equal in diameter to the filament. 



