FRESn-WATER A L G yE O F T H E U N I T E D S T A T E S. 53 



well shown in figure 2 b, pi. 5. Associated with them were a number of similar cells 

 which had not obtained as yet the outer thick Avail. The color of the filaments is 

 in my specimens of a rich golden brown ; but, as they have been preserved in car- 

 bolic acid water, I cannot speak positively as to the original tint. The heterocysts 

 are subglobose, sometimes compressed, sometimes somewhat triangular. They 

 about equal in diameter the internal filament. 



Fig. 2, pi. 5, represents a small cluster of youngish filaments of this species. 



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



M. tliallo cespitulo, molle, piirasitico ; trichoraatibus siniplicibus, pleninique inartipulatis, Red, 

 iuterilum breve, interdum longe, articulatis, coiitinuis, rariiis inti'rniptis, apiee attenuatis, 

 flaTO-olivaceis aut viridibus, sparse grauulatis ; vaginis jikTunuiuf aniplis et distinctis, liya- 

 linis, SGepius valde undulatis, apice plerumque valde amplilicatis et in fibrillas solutis ; cellulis 

 perdurantibus dianietro subsequalibiis ; sporis nullis. 



7)(a„i.— Tnchoni ■^^^^" = .000 IG"; cum vag, jj,'^/ = .0005". 



Hah. — III plantiirum aquaticarura foliis. Carp River, Michigan. 



Tballiis somewhat ca;spitose, soft, parasitic; filaments simple, mostly inarticulate, but some- 

 times shortly sometimes long articulate, continuous or more rarely interrupted, attenuate at 

 the apex, yellowish-olive or greenish, sparsely granulate; sheaths mo.stly ample and distinct 

 hyaline, often strongly undulate, the apex mostly much amplified and dissolved into fibrillar; 

 heterocysts about equal to the filament in diameter; spores wanting. 



BemarJiS. — This species was found in the Carp River bog, growing on the edges 

 of minute leaves, so as to form little prominences or thickenings of the margin. 

 The trichomata are quite distinct from one another, and can scarcely be said to be 

 united into a frond, although they all appear to radiate from the base, where they 

 are consolidated into a dense mass. The sheaths are generally quite distinct, much 

 broader than the cytioplasm, and are not sensibly dilated below. In most si)cci- 

 mens they are very distinctly alternately dilated and contracted, or in other words, 

 midulated. This is especially the case when the sheaths are quite wide. Above, 

 they are rapidly and widely dilated, are distinctly fibrillose, and appear to gradu- 

 ally melt away. The cytioplasm is rarely articulated, and, wlien it is so, the joints 

 are scarcely longer than broad, and are most generally confined to the distal end of 

 the filament. Thg species appears to be most nearly allied to M. Bauerlannw, 

 Grun., from which, however, it is quite distinct. 



Fig. 2 a, pi. 4, represents this species magnified 250 diameters ; fig. 2 h, a single 

 filament magnified 800 diameters. 



M. clongntiim, Wood. 



M. initio subglobosum, postea siepe nonnihil fusinnm, nigro-viride, liibricum, Crme ; triclioma- 



tibus aerugineis, valde elongatis, flagelliformibns, interdum inarticulatis sed siEpius breve 



articulatis, interdum ad genicula valde constricti.'i, apice interdum truncatis sed plerumque 



in pilum, longum, achroum, flexnosum, produetis; vaginis achrois, arctis, sa;pe apice trun- 



^ catis ; cellulis perdurantibus globosis vel subglobosis. 



Biam — j^ji-s" = .0002G." 



Syn. — M. elongatiim, Wood, Prodromus, Proc. Amer. Philos. Soc, 1800, p. 128. 



Hab. — In aquario. 



