FRESH-WATER ALQM OF THE UNITED STATES. 45 



KT. lobaf IIS, Wood. 



N. tballo vivide viritle aut luteo-viride, cave, enormiter lobato, uataute, modice ma^no, firrao 

 gelatinoso ; tricboiuatibus plerumque longis, fle.xuosis, dilute viridibus, plerumque artieulatis, 

 partim inarticulatis, cylindricis aut sub-moniliformibus, sparse granulatis. 



Z>iam.— Trichom. Tsi^/ = .00006"— t^l^j" =, .00013" ; cell perdum. ^^'j^" = .00026". 



Syn. — N. lohalus, Wood, Prodromus, Proc. Amer. Philos. See, 1869. 



Hub. — In Schuylkill Flumine, prope Philadelphia. 



Thallu.s bright green or yellowish-green, hollow, irregularly lobed, floating, moderately large, 

 firm, gelatinous; filaments mostly long, flesuous, dilute green, mostly articulate, partly inar- 

 ticulate, cylindrical or somewhat moniliform, sparsely granulate. 



Remarhs. — I found this plant floating upon the Schuylkill River just above 

 Manayunk. The hollow frond was buoyed up by a bubble of gas contained within 

 it. It was an irregular, flattened, somewhat globose mass, of a bright green color 

 and about half an inch in diameter. It seems very probable that in its earlier 

 condition, it was a solid attached frond. The long slender filaments are often very 

 tortuous, but run a pretty direct general course towards the outer surface. 



Fig. 6 rt, pi. 3, represents a section of the frond slightly magnified ; a, h, c, por- 

 tions of filaments magnified 800 diameters. 



Genus GLOIOTRICHIA, J. Ac. (1842.) 



Trichomata e planitie orta pseudoramosa, distincte vaginata ; vaginae amploe, basi plerumque 

 saccata;, transverse undulato-plicatee, plus minus constrictae, apice apertae, uon laciniatae. SporaB 

 magnse cylindrica9. 



Filaments springing from a plane, pseudoramose, distinctly vaginate ; sheath ample, mostly 

 saccate at the base, transversely undulately plicate, more or less constricted, open at the apex, 

 not laciniate. Spores large, cylindrical. 



Remarks. — This genus was, I believe, first indicated by Professor Agardh in 

 his Algce Maris Mediterranei et Adriatiei, a work to which I have not access. 

 On account of tliis, and also because I have not seen any of the typical species 

 of the genus, I have preferred simply copying the generic characters given 

 by Professor Rabenhorst. If my understanding of " e planitie orta" is cor- 

 rect, I do not think it true. Professor Rabenhorst's own figure of Rivularia 

 shows that the filaments do not all arise on one plane ; although he asserts the 

 character equally for tliat genus. In our American species the filaments do not 

 all arise on one plane, nor can they be spoken of as "^JsertcZoramosa." 



G. incrustata, Wood. 



G. globosa vel subovalis, firraa, solida, ad pisi minimi magnitudinem, dilute viridis, crystallo- 

 phora; trichoraatibus rectis aut leviter curvatis, in pilum productis, viridibus aut flavcscen- 

 tibus, SEepe infra Isete viridibus sed supra flavescentibus, hand ordinatira artieulatis; articulia 

 inferioribus in trichomatibus maturis brevibus, plerumque eompressis ; pilo apicale recto aut 

 leviter curvato, plerumque indistincte articulato. soepe interrupto; vaginis araplis, achrois, 

 saccatis, interdum valde constrictis ; sporis cylindricis, saepe curvatis, diametro ad !) plo lon- 

 gioribus ; cellulis perdurantibus sphaericis. 



