FHKS II WATER A L & OF T II K U N I T E D STATES 97 



"What becomes of them after this, as h is been stated, is a mere matter of conjec- 

 ture. M. braun 1 ami others have described unicellular forms of several of the 

 imilticelhilar species of 1',- /i<t*intin, and I'ringsheitn suggests that these are really 

 polyhedrons developed out of these microgonidia, as is seen in the water-nets. 

 This, of course, may or may not be the case. 

 P. Ilorvaiiuiii. (Ti KI-IM MKN..H. 



P. coenobio orbicular!, oblongo vel elliptico, magnitudino vario, continue, Isete viridi, c cellulis 

 4-8-16-82-64 (rarissirue 128) composite (ci-llulunim strato Bimplici, nonnunquam medio 

 duplicate); cellulis periphericis plus minus profunde emarginatis vel bilobis, lobis cornutis, 

 cornibus achrois hyalinis, abbreviatis Tel elongatis, teretibus, obtusis vel subobtusis, interdum 

 capiu-lluto-iiicrassatis, centralibus nrctissime concretis, polygonis (4-6 angularibus), in antica 

 parti- modo angulo prominnlo raodo plane truncatis, modo leviter repandis, omnium mem- 

 brana dcciiRsatim punctata. (R.) 

 >tom. Transv. cell 0.000795"; rarius 0.00088" 0.00094". (R.) 



Syn. P. Boryanum, (TuRpiN,) MENOHINI. RABENHORST, Flora Europ. Algarum, Sect III. 



P. 74. 

 Hub. Georgia, Florida, Rhode Island, Bailey ; Pennsylvania, Wood. 



(Ylls arranged in one or more circles round one or two central cells; the inner variable, generally 



concave at one side, the outer tapering into two long subulate points, the notch narrow. 

 L. 1-2083" to 1-1633"; B. 1-2733" to 1-2222". (Archer.) 



P.Selenwa, KTZ. 



1'. KI nol.io orbicular!, integro, e cellolis 8-16 (rarius 31 = 1 -f- 5 + 10 + 15, KTZ.) fonnato; 

 ccllulis periphericis angustia, lunatis, acute lobatis, disci cellnlis leviter excisis, central! unica 

 5-angulari, omnium membrana firma, snbcrassa, aetate provecta rubesccnte. (R.) 



Diam. Ccenobii 0.00124" 0.0035"; cell, (distant!* interlobos) 0.00026" 0.00069". (R.) 



a.P.Selensea, KTZ. RABENUORST, Flora Enrop. Algarnm, Sect. III. p. 73. 

 llnb. Rhode Island, Bailey. 



Cells crescent-shaped, arranged in one or more circles round one or two central ones, connecting 

 medium colored. (A.)' 



P. pcrtiiMiim, KTZ. 



P. coenobio orbicular!, lacunis pcrtuso, magnitndine vario, e cellnlis plernmqne 1 + 5+10 + 15 

 (in fortnis quibusdam ad 64) composite ; cellnlis periphericis basi tantum laxe connexis, ad 

 medium usque bilobis, lobis rectis, in cornna hyalina modo subacuta modo obtusa vel trnn- 

 cata plus minus productis, centralibus plus minus exacto quadrangularibns, et in antica parte 

 et ntrinque umaginatis, omnibus Uevibus, locellis pallioribus finis instructis. (R.) 



Diam. Transv. cell, perfect evolnt circiter 0.00065" 0.00089". (R.) 

 Syn. P. pertusum, KTZ. RABENHOBST, Flora Europ. Algarnm, Sect. III. p. 75. 

 Cells arranged in circles round one or two central ones; inner cells quadrangular, sides concave 

 and leaving angular vacant intervals; the outer cells with square bases, externally triangu- 

 larly notched, the subdivisions tapering to an acute point L. 1-2266" ; B. 1-3268". (A.) 



P. constrictum, HASSAL. 



P. coenobio orbicular! vel suborbicnlari, Isete viridi, continno, Itevi ?, e cellulis 16 (ad 1 + 5 + 

 10) vel 32 (ad 1+6 + 10 + 15) formato; cellnlis periphericis irregulariter bilobis, sinu 



1 The best exposition of this genus is to be found in Braun's Unicellular Algse. 

 ' The letter A used here signifies that the description is copied from Mr. Archer in Prichard's Infu- 

 soria. 



13 June. 1872. 



