FRESH-WATER ALG^ OF THE UNITED STATES. 121 



P. constrictum, (Bailet) 



D. subvalidum, lasve, latitudine 10-12 plo longius, medio valde constrictum, stricturas margine 

 non prominente ; cruribas a basi tumida in apicem late truncatum non attenuatis, 4 undu- 

 latis. (R.) {Species mihi ignota.) 



Si/n. — Docidium constrictum, Bailey. Ralfs, British Desmids, p. 218. 



Hab. — Rhode Island, Bailey. 



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

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

 by the cross section of the nodes being a simple circle instead of an indented one,' Bailey." 

 Ralfs. 

 P. Terrucosum, (Bailey) 



D. validum, granuloso-verrucosum, latitudine 10-12 plo longius, nndulatum, apicibus integris 

 truQcatis. (R.) {Species mihi ignota.) 



Syn Cosmarium verrucosum, Bailey, Amer. Journ. Sci. and Arts, 1846. 



Docidium verrucosum, Ralfs, Brit. Desm. p. 218. Bailey, Micr. Observ. p. 28. 



Hab. — 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- 

 line, caused by the slight projections, which are arranged in numerous transverse rings,' 

 Bailey." Ralfs. 



P. hirsutum, (Bailey) 



D. spinuloso-hirsutum, medio valde constrictum, diametro 10-12 plo longius ; crnribus et basi 

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



Syn. — Docidium hirsutum, Bailey, Micr. Observ. p. 36. 



Sab. — Florida; Bailey. 



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

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

 face." Bailey. 



Genus TEIPLOCERAS, Bailet. 



Cellulse singulae, rectae, valde elongatae, processus magnorum seriebus transversis armatae, utroque 

 polo trilobatsB, lobis acute bidentatis. 



gyn. Triploceras, Bailey, Microscopical Observations, p. ST, Smithsonian Contributions, 1850. 



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

 bate at each end, lobes acutely bidentate. 



T. Terticillatum, Bailey. 



T. cellnlis subcylindricis, sed utroque fine leviter angustatis et nonnihil fusiformibus, modice 

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

 emarginatis. 

 Diam.—Cnm process. jlW = -00146" ; sine process. ttVW = -00113". 

 Syn.— T. verticillatum, Bailey. Microscopic Observations. Smithsonian Contributions, 1850. 

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

 Pleurotsenium verticillatum, Rabenhorst, Flora Burop. Algar., Sect. III. p. 148. 



Ba6.— Rhode Island, New Jersey, Georgia, Florida ; Bailey. Saco Lake, (Dr. Lewis) Wood. 



Subcylindrical, 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 Jane, 1872. 



