98 FRESH-WATER ALG^ OF THE UNITED STATES. 



angusto, lobis in^qualibus, basi plerumque constrictis, in cornua subcrassa obtusa productia. 



centralibus polygonis, in antica parte repandis. (R.) 

 Syn.—P. ellipticum, Hassal. Rabenhorst, Flora Europ. Algarnm, Sect. Ill, p- 7T. 

 Sab.— South Carolina, Georgia, Rhode Island, Bailey. 

 Cells varying in number and arrangement; outer cells suddenly contracted into two short, 



cylindrical, obtuse processes. L. l-lt54" to 1-906"; B. 1-1515" to 1-1020 

 0, Processes of the lobes truncately emarginate. (A.) 



P. Ehrenbergii, (Coeda) Bratjn. 



P. coenobio et orbiculari et oblongo, perfecte clauso, e cellulis 8 vel 16 composito et quadrate, 

 e cellulis 4, late cuneatis, profunde lobatis, exacte cruciatim dispositis formato ; celluhs pen- 

 phericis cuneatis a basi truncata ad apicem usque concretis, profunde bilobis sinu angusto, 

 lobis sspe oblique truncatis, plus minus sinuato-exeisis, angulis interioribus ad duplum lon- 

 gioribus, omnibus acutis vel breviter appendiculatis ; cellulis centralibus aut singulis aut 

 pluribus (2-5-6 v. 8), omnibus flavo-viridibus, polygonis, uno latere repandis vel profunde 

 incisis. (R.) 



Syn.—P. Ehrenhergii, (Corda,) Braun. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 77. 



^a6.— South Carolina, Georgia, Florida, Rhode Island, Bailey. 



Frond minute ; cells eight (seven disposed in a single series round a central one), bilobed,. 

 angular. L. 1-2900" ; B. 1-2500". (A.) 



P. simplex, Meyen. 



P. cellulis periphericis ovato-cuspidatis, 8-10-16 basi tantum concretis, circulum simplicem 

 constituentibus, centralibus saepe nullis. (R.) 



Syn. P. simplex, Meyen. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 71. 



Monactinus octonarius, Bailey, Smithsonian Contributions. 

 Sab. — South Carolina, Rhode Island, Bailey. 



Far.— duodenarius. 



Coenobio clathrato, cellulis periphericis 12, centralibus 4, regulariter cruciatum dispositis. (R.) 



gyn. — Monactinus duodenarius, Bailey. 



Inner cells four, somewhat triangular, enclosing a central, quadrate vacant interval, and four 

 broadly lanceolate vacant intervals between them and the outer series, to which they are 

 united by their terminal angles, outer cells twelve, subovate, truncate below, much attenuated, 

 acuminate. (A.) 



Family VOLYOCINE^. 



Coenobia mobilia, globosa, subglobosa vel quadrangulo-tabulata, e cellulis viridibus cilia bina 

 agilia gerentibus, intus vesica duplici contractibili prseditis composita, membrana (tegumento, 

 chlamyde) communi achroa hyalina plus minus ampliata involuta. 



Propagatio aut sexualis, monoica vel dioica (ad hue in paucis tantum generibus probata) ; cellulis 

 coenobii aut omnibus aut quibusdam genus masculinum vel feminum exhibentibus, illis in fascicules 

 spermatozoideorum (autheridia), has in oosporas episporio inclusas, non mobiles commntatis, aut 

 non sexualis, gonidiis agilibus, (et macrogonidiis et microgonidiis — etiam zoogonidia vocantur). 

 Macro- et microgonidia (cellulse primordiales) cytioplasmatis divisione simultanea et multiplici orta ; 

 priora numero definita (2-4-8-16, &c.), majora oblonga vel rotundata, polo antico plus minus rostri- 

 formi producta, ciliis binis per vesicae membranam exsertis, puneto (ocello Ehrberg. stigma) sanguineo 

 centrali vel parietali et locellis (vacuolis) ssepe binis contractibilibus instructa; ultima numero indefi- 

 nita, multo minora, pallide vel sordide viridia vel luteola, apice ciliis instructa, plerumque jam intra 

 cellulam matricalem vivide vacilkntia, postea membranae ruptura libere erumpentia, examinantia. (R.) 



