FKKSH- WATER ALGJS OF TUB UNITED STATES. 121 



P. conwtrirtiim, (BAILEY) 



D. subvalidum, lasve, latitudinc 10-12 plo longius, medio valdc constrictura, stricture margine 

 noil proiniuente ; cruribus a basi tutuida hi apictnu lute truucatuiu uon atlenuatis, 4 umlu- 

 liitis. (H.) (.S/xvifi mtfii iynuta.) 



Syn. Docidium constrictum, BAILEY. RAITS, British Desmids, p. 218. 

 llab. Rhode Island, Bailey. 



" Frond stoat, segments with moderately deep constrictions, which separate four equal, gently 

 curving prominences ; end view entire. ' This species is at once distinguished from /'. nodosum 

 by tin- iTn.-s suction of the nodes bciug a simple circle instead of an indented one,' Bailey." 

 Half*. 

 P. TrrrucoMum, (BAILEY) 



I> vulidum, granulosc-vcrrucosnm, latitudine 10-12 plo longiui, undulatum, apicibus integria 

 truucatis. (II.) (Species mihiiynota.) 



Syn Cosmarium verrucosum, HAILKY, Araer. Journ. Sci. and Arts, 1846. 



Docidium verrucosum, RALFS, Brit. Desm. p. 218. BAILEY, Micr. Observ. p. 28. 



Hub. Rhode Island ; Bailey. 



"Segments, with numerous whorls of small prominences, which give the margins an undulated 

 appearance, all the undulations are equal. ' This is a very pretty species with a waved out- 

 lii.e, caused by the slight projections, which are arranged in numerous transverse rings,' 

 Bailey." Haifa. 



P. Itir-ntiim, (BAILEY) 



It. spinuloso-hirsutum, medio valde constrictura, diametro 10-12 plo longins; crnribns ct basi 

 et apice subdilatatis, truucatis. (R.) (Species mihi ignota.) 



Syn. Docidium hirsulum, BAILEY, Micr. Observ. p. 36. 

 Bab. Florida; Bailey. 



"Segments many times longer than broad, slightly inflated at the base, surface hirsute. A 

 small species resembling 1>. Ehrenbergii in its form, but strongly hirsute on its outer sur- 

 face." Bailey. 



Genus TRIPLOCERAS, BAILEY. 



Cellule singulte, rectse, Talde elongate, processus magnorum scriebus transvereis armatse, utroqne 

 polo trilobatie, lobis acute bidentatis. 



Syn Triploceras, BAILEY, Microscopical Observations, p. 37, Smithsonian Contributions, I860. 



Cells single, straight, very much elongate, armed with transverse series of large processes, trilo- 

 bate at each end, lobes acutely bidentate. 



T. verticillatum, BAILEY. 



T. cellulis snbcylindricis, sed ntroqne fine leviter angustatis et nonnihil fusiformibus, modice 

 robustis, diametro 12-20 plo longioribus; processibus lateralibus robnstis, magnis, apice 

 emarginatis. 

 Diam. Cum process. 7 Jfo" = .00146"; sine process. T ^,W' =-00113". 



Syn. T. verticillatum, BAILEY. Microscopic Observations. Smithsonian Contributions, 1850. 

 Docidium verticillatum, RALFS, British Desmids, p. 218. 

 Pleurotienium verlicillatum, RABENHORST, Flora Enrop. Algar, Sect. III. p. 148. 



Hob. Rhode Island, New Jersey, Georgia, Florida ; Bailey. Saco Lake, (Dr. Lewis) Wood. 



Snbcylindrical, but slightly narrowed at each end, and therefore somewhat fusiform, moderately 

 robust, 12-20 times longer than broad; lateral processes large, robust, with their apices 

 emarginate. 

 16 June, 1871. 



