98 FRESH-WATER A L G M OF THE UNITED STATES. 



nngusto, lobis inaequalibns, basi plerumque constrictis, in cornua subcrassa obtusa productis, 

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



Syn. P. ellipticum, HASSAL. RABENHORST, Flora Europ. Algarum, Sect. Ill, p. 77. 

 Hab. South Carolina, Georgia, Rhode Island, Bailey. 



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



cylindrical, obtuse processes. L. 1-1754" to 1-906"; B. 1-1515" to 1-1020". 

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



P. Ehrenbergii, (COBDA) BRAUN. 



P. cosnobio et orbicular! et oblongo, perfecte clause, e cellulis 8 vel 16 composite et quadrato, 

 e cellulis 4, late cuneatis, profuude lobatis, exacte cruciatim dispositis formato ; cellulis peri- 

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

 lobis saepe oblique truncatis, plus minus sinuato-excisis, angulis interioribus ad duplum lon- 

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

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

 incisis. (R.) 



Syn. P. Ehrenbergii, (CORDA,) BEAUN. RABENHORST, Flora Europ. Algarum, Sect. III. p. 77. 

 Hab. 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 peripheries ovato-cuspidatis, 8-10-16 basi tantum concretis, circulum simplicem 

 coustituentibus, centralibus ssepe nullis. (R.) 



Syn. P. simplex, MEYEN. RABENHOKST, Flora Europ. Algarum, Sect. III. p. 71. 



Monactinus octonarius, BAILEY, Smithsonian Contributions. 

 Hab. South Carolina, Rhode Island, Bailey. 

 Var. duodenarius. 



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

 Syn. 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 VOLVOCINE^E. 



Crenobia 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 (adhuc in paucis tantnm generibus probata) ; cellulis 

 coanobii ant omnibus aut qnibusdam genus masculinura vel feminnm exhibentibus, illis in fasciculus 

 spermatozoideorum (autheridia), has in oosporas episporio inclnsas, non mobiles comrnutatis, aut 

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

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

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

 formi producta, ciliis binis per vesicse membranam exsertis, puncto (ocello Ehrberg. stigma) sanguineo 

 central! vel parietali et locellis (vacuolis) saepe binis contractibilibus instructa; ultima numero indefi- 

 nita, multo m.nora, pallide vel sordide viridia vel luteola, apice ciliis instructa, plerumque jam intra 



lulam matricalem vmde vacillantia, postea membranse ruptura libere erumpeutia, examinantia. (R ) 



! 



