FRESH-WATER ALG^ OF THE UNITED STATES. 51 



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

 filaments generally slraightish, 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-seriate. 



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

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

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

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

 trichoma or filaments 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 the homoge- 

 neous jelly, in which the filaments are imbedded. The basal cell is large, 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 sheath, 

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

 very short, rather distinctly separated, almost globular. 



Fig. 5, pi. 4. 



Genus MASTIGONEMA, Schwabe. 



Trichomata articulata, sursum flagelliformia vel subulata, simplicia vel pseudoramosa (nonnunquam 

 fascicnlatim pseudoramosa), proeumbentia vel erecta, in thallo indistincto csespitoso-aggregata ; 

 vaginae arctae et homogeneae vel amplse et plus minus distincte lamellosse, apice plerumque apertae, 

 interdum laciniatae. 



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

 fasciculately so, procumbent or erect, caespitosely 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. 



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



M. caespitosnm, cum algis alteris intermixtum ; triehomatibns simplieibus, elongatis, flexuoso- 

 enrvatis, apice truncatis; trichomatibus internis viridibus, saepe interruptis, interdum dis- 

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

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

 sparsis, in filamento unico saepe pluribus, in cellulis inclusis ; cellulis perdurantibus globosis, 

 interdum eompressis trichomatis diametro fere aequalibus. ^ 



Xlifflm.— Filam, ^^" ^ .00033" ; spor. ^^Vtt" = .OOOiee". 



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



Caespitose, intermixed with other algae; 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 thdir 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. 



