FRESH-WATER A L G .E OF THE UNITED STATES. 13 



cells, each of which has a distinct tegument, the whole luring surrounded with that of the old mother- 

 cell. This process of division i- tlien repeated airain and again, the original cell-wall remaining and 

 surroumliiitr the family thus funned. (.'ytiudenu thick, ofti-n very thick, e([ii;illing, or exceeding in 

 diameter the cavity of the cell, achromatic or colored, mostly laraellated, lamcllie or strata not rarely 

 si-parating. Cytioplasm of various colors, icruginniis, dlni-li-grecn, chalybeate, reddish, yellowish- 

 fuscous, Ac. Division of the cells occurring in three directions. The last generation of cells smaller 

 than the earlier ones. 



CJ. par*n, WOOD. 



U. in strato mucoso sociis algis variis sparsa; cellnlis sphiericis, vel oblongis vel ovatis, 2-8 in 



familia* consiwiatis; fumilii.s subglobosis vel subovntis, interdnm nnmeroso-aggregatig ; tegu- 



racntis inti-rnis aureofu-cin, firmis, rarissime coloris expertibus, homogcncis, vel lamellosis; 



tepnnu-nti exiiTiiis uehromaticis, rare subachromaticis, plernuiqae vix visibilibus; cytioplas- 



mate homogcnco. 

 Diam. Max. cell, oblong, sine tegnm. long., y j vv "; lat, 75*05"; cell, glob., sine tcgum., 



>"; cum tcgura., TI ' T i"; fam., 7 }j". 



.s'yn. f!. sparta, WOOD, Prodromus, Proc. Amcr. Philos. Soc., 1869, 123. 

 IM>. In rupibus irroratis prope Philadelphia. 



ii scattered in a mucous stratum composed of various algae ; cells spherical, or oblong, or ovate, 

 associated tiijrcther in families of from 2-8; families subglobose or subovate, sometimes aggre- 

 gated loir. .||ii-r in large numbers; inner tegument yellowish-brown, Grin, rarely colorless, homo- 

 geneous or lamellate ; external tegument achromatic, rarely subachromatic, generally scarcely 

 visible. 



/,'< marks. This species was found in a rather firm, grumous or gelatinous coat- 

 ing of a light brown color, growing on the rocks at Fairmount Water Works, 

 chiefly composed of a very minute nostochaceous plant, but contained numerous 

 other alir;i\ The color of the tegument is yellowish-brown, sometimes with some- 

 red in it, sometimes with something of a greenish tint. This inner colored coat 

 is not generally more than once or twice lamellate, often it is not at all so. This 

 species seems somewhat allied to 0. 8(i/<>j>fi!ln, but differs slightly in the form of 

 tin- cell, and more especially in not having a distinct thallus, and iu the families 

 beiiii,' small and containing but few cells. 



Fig. 7, pi. 8, represents this species, magnified 750 diameters. 



Genus CLELOSPH^ERIUM, NJEGELI. 



Thallns parvns, c cellulis minimis in familias peripheries consociatis vel in stratum pcriphcricum 

 simplex et in muco tegamcntis celerrimc con fluent! bus formato nidulautibus compositus. Ccllu- 

 larum divisio, initio generationum serierum, in omnem Gt dircctionem, turn deoiqae alternatim 

 ad superficiei splncricic utramque directioncra. 



Thallns small, composed of very small cells consociated into peripheral families, or in a simple 

 peripheral layer, inclosed in their quickly confluent teguments. Division of the cells at first in all 

 directions, afterwards only in each direction on the surface of the sphere. 



C. dubium, GRIN. ? 



C. thallo microscopico, snbgloboso vel cnorme, natante, congregate; cellnlis globosis ant sub- 

 globosis; cytioplasmate pallide airngineo, snbtiliter granulato. 



Diam. Cell, plemmqnc '*" -00016"; rare ,^5" = .00025"; fara. T W" 

 .00083" .0033". 



