146 FRESH-WATER ALGJS OF THE UNITED STATES. 



Diam. 0051" .0078". (R.) 



Syn. M. fimbriata, RALFS, British Desniidiese, p. 71, et RABENUORST, Flora Europ. Algarum, 

 Sect. III. p. 193. 



Hob. South Carolina ; Florida ; Bailey. 



Frond orbicular, smooth ; segments 5-lobcd, basal lobes twice, middle lobes thrice dichotomous ; 

 ultimate subdivisions acutely bidentate; end lobe very slightly exserted, its angles very 

 slightly produced, bidentate, ends emarginate. In transverse view is seen an inflated pro- 

 tuberance just over the central isthmus, which may possibly exist in other species of Hicras- 

 terias. (A.) 



HI. papillifera, BREB. 



M. orbicularis, superficie lajvis, margine extremo dcntato papillifera; sernicellulis quinquelobis; 

 lobis basalibus et interniediis ffiquilatis, bilobatis ; lobulis biiidis, laciniis linearibus bidentatis, 

 dentibus papilliferis ; lobo polari vix promiuulo, in apice siuuato, angulis et margiue dentato- 

 mucronatis. (R.) Species mihi ignota. 



Diam. 0.0045". (R.) 



Syn. M., papillifera, BREBISSON. RALFS, British Desmidiete, p. 72, et RABENUORST, Flora 

 Europ. Algarum, Sect. III. p. 194. 



Hob. Florida ; Rhode Island ; Bailey. 



Frond orbicular, having the principal sinuses bordered by a row of minute granules, otherwise 

 smooth ; segments 5-lobed ; basal and middle lobes twice dichotomous, their ultimate shal- 

 low subdivisions terminated by two, sometimes three, gland-like teeth ; end lobe emarginate, 



its angles dentate. Sporangium as in M. denticulata, but considerably smaller. (A.) 







Ifl. granulata, WOOD (sp. nov.) 



M. magna, suborbicularis, arete granulata ; semicellulis quinquelobis, lobis inter se sinu angusto 

 discretis, basalibus et interniediis plerumque integris, lobo polari supra valde dilatato, in 

 dorso medio leviter retuso ; marginibus valde crenatis. 



Diam. Long, ^h" = -0043". Lat. T5 4 5 V' = -0036". 

 Hob. South Carolina, (Ravenel) 



Large, suborbicular, closely granulate; semicells Wobed, lobes separated by narrow sinuses; 

 basal and intermediate lobes mostly entire; end lobe distally broadly dilated, broadly and 

 very shallowly emarginate ; margin of frond strongly crenate. 



Remarks. The only specimens of this species that I have seen were collected by 

 Prof, ftavenel in a shallow ditch near Aiken, South Carolina, where they formed a 

 greenish, gelatinous mass, with numerous desmids and diatoms. It is most closely 

 allied to M. truncata, from which it is separated by its entire lateral lobes, by its 

 granulated surface, and its crenated margins. It also does not apparently attain 

 as large a size as that species. The granules are very small in the central portion 

 of the frond, but become larger as they approach the margin. 



Fig. 16, pi. 21, represents an empty frond of this species, magnified 460 diam- 

 eters. 



M. Jenneri, RALFS. 



M. magna, oblonga, plerumqne snbtiliter granulata; semicellulis quinquelobis; lobis basalibufl 

 et intermediis sequilatis, confertis, cuneatis, bilobulatis ; lobo polari late truncate vel late 

 rotundato, in medio interdum leviter et obtuse emarginato, interdum nonnihil profunde emar- 

 ginato. 



Diam. Lat. T f gj 'rff vt * = .006" .0062". Long. 7 f 5 "_ T ,y^" = . 0062". 0087". 



