FRESH-WATER ALG.tt OF THE UNITED STATES. 145 



country, but 1 have never met with it. All the specimens which have come under 

 my notice \M ic obtained in "Shepherd's Dam," near Greenwich, Cumberland 

 County, New Jersey. None of them were as large as the maximum of the European 

 measurements of which llabenliorst gives 0.0109" as the diameter. 



Fig. o, pi. l;3, represents a frond of this species, magnified 260 diameters. 



.71. denticulata, BHEB. ? 



M (.cniiniritu, paulo longior quain lata, Itrvis; semicellulig quinquclobis (ptene 9 lobis) ; lobis 

 intrrmediis et basalibus simillimis, bilobatis, lobulis item in lobulis bifidis duobus divisis ; 

 lobo polare angusto, cuncato, in apice plus minus inciso ; margine minute denticulato. 



IHam.LtA. .0092". Long. .011." 



>'i/;i. M. <!ftt,-ttlala, .BREBissoN. RALFS, British Desmidicse, p. 70, et AKCIIER, FRIT-CHARE'S 



Infusoria. 

 M. denticulata, BREBissox. ? RABENHOR8T, Flora Europ. Algarum, Sect III. p. 192. 



Ilab. Pennsylvania; Wood. Florida; Bailey. 



Vi-ry large, a little longer than broad, smooth; semicells with five lobes (scarcely 9); basal 

 and intermediate lobes alike bilobate, lobules also divided into two bifid lobules; end lobe 

 narrow, wedge-shaped, more or less incised at its apex ; margin minutely denticulate. 



L'> marks. Prof. Rabenhorst gives M, denticulata, BREB. as merely a variety of 

 M. r'/irriiin, Ac., stating that it only differs from the latter in the marginal incisions 

 and teeth. Not having access to the original description of Brebisson I cannot 

 express an opinion as to whether Prof. R. is correct or not, but the specimen from 

 which the above description was drawn up (and which is figured on plate 13) cer- 

 tainly differs from M. furcata very essentially in the arrangement of its lobes, and 

 is, I feel confident, M. denticulata, BREB. of RALFS and ARCHER. 



Fig. 6, pi. 13, is a drawing of this plant, as seen by myself, magnified 260 

 diameters. 



ffl. radio*.-!, Ao. 



M. maxima, orbicularis, Isevis, antecedent! simillima, diflcrt in prim is segmentis ultimis turoidis 

 in apicem bi- tri- fidum attenuatis, lobo polari vix prominulo, apicc sinuate, ad ntrumque 

 angulum bi- tri- dentato. (R.) Species mihi ignota. 



Diam. 0.0076". (R.) 



Syn. M. radiosa, AoARDn. RABENHORST, Flora Enrop. Algarum, Sect III. p. 192. 



Hob. Florida; Bailey. 



Frond orbicular, smooth ; segments 5-lobed ; basal lobes twice, middle lobes generally thrice 

 dichotomous, ultimate subdivisions inflated, attenuate towards the end, bidentate; end lobes 

 emarginate, its angles dentate. (A.) 



in. fimbriata, RALPS. 



M. magna, orbicularis, laevis (nonnunqnam superficie aculeis singulis sparsis); semicellulis 

 quinquelobis, lobis omnibus confertis, basalibus angustioribus, repetito bilobulatis, lobis inter- 

 mediis duplo latioribus, repetito-bilobulatis, lacinnlis extremis levitcr emarginatis, in angulis 

 apinis elongatis armatis; lobo polari prominnlo, in apice obtuse sinuato-vel-undulato-emar- 

 ginato, angalis lateralibns rotnndatis, ad marginem superiorem spiuis singulis vcl geminis 

 obsito (rarius nndo). (R.) Sjtecies mihi ignota. 



19 August. 1873. 



