R ALU.K OK T II K UNITED STATES. 45 



IV. lobatiiM, \V<>OD. 



N t hullo vivide riride aut luteo-Tiridc, cavo, enormiter lubato, nalaiite, modice raagno, firmo, 



ru-li'MiiutilMi-. |ili-ruiii.|iii- l.iu^i-, ll.-xuoMs, dilute viridibus, plcramque articulatis, 

 part im iuarticulalis, cvlimlriris uul sub-nioiiiliformilius, .-purse granulalis. 



/'mm. Trirliura. TI i e j" - .00000" yj 1 ,/ .00013" ; cell perdum. "" - .00026". 

 .Sy/i. ff. lobatu*, Wixm. I'rmlroimis, 1'n-c. Amcr. 1'hUos. Soc,, 1869. 

 Ilab. In Srhuylkill Klumioe, prope I'liiludrlphia. 



Thiillus lirijrlii uTi-i'ii or vrllowi.sh-grreii, hollow, irregularly lohod, floating, moderately large, 

 firm, p-laiinniis ; tilaim-nis mostly lonir, flcxuous, dilute trn-cn, mostly articulate, partly iiiar- 

 tiruluto, cylindrical or somewhat moniliform, sparsely grauulate. 



It- murk*. -I found this plant floating upon the Schuylkill River just above 

 M;m;i\ link. The hollow from! 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 alxmt half an inrh 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. 



I u r (> ". pi. 3, represents a section of the frond slightly magnified; a, 6, c, por- 

 tions of filaments magnified 800 diameters. 



Genus GLOIOTRICHIA, J. Ac. (1842.) 



Trichomata e planitie orta pseudoramosa, distinctc vaginata; vaginee amplae, Imsi pleramque 

 accaUe, transverse undulato-plicate, plus minus constricUe, apice apertae, non laciniatae. Spore 

 magnw cylindrical. 



Kilaments springing from a plane, pseudoramosc, distinctly raginate ; sheath ample, mostly 

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

 nut laciuiate. Spores large, cylindrical 



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

 his Alijcc Maria Mediterranei et Adriatic*, a work to which I have not access. 

 < )n account of this, 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 that genus. In our American species the filaments do not 

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



< incrustata, WOOD. 



O. globosa rel oubovalis, firma, solida, ad pisi minimi magnitudincm, dilate viridis, crystallo- 

 phora; trichoraatibus rectis aut leviter curvatis, in pilum productis, riridibus ant flavescen- 

 tibus, sepe infra loete viridibns sed supra flavescentibns, haad ordinatim articulatis; articulis 

 inferioribns in trichomatibus maturis breTibns, plerumqne compressis; pilo apicale recto aut 

 letiter curvato, plerumque indistincte articulato, saepe interrupto; vaginis amplis, achrois, 

 saccatis, intcrdum valdc constricti." ; spot-is cylindricis, saepe curvatis. diametro ad 9 plo lon- 

 gioribas ; cellulis pcrdurantibas sphaericia. 



