fuesh-water alg^ of the united states. 11 



Genus CHEOOCOCCUS, N^geli. 



CellulsB globosse ovales vel a pressione mutua plus minus angulosas, solitariae vel in famiiias con- 

 sociatse, libersB (a vesica matricali non involutee) ; cytiodermate achromatico, homogeneo, ssepein muco 

 plus minus firmo confluente; cytioplasmate seruginoso vel pallide caeruleo-viridi, non rare luteolo vel 

 aurantiaco, iuterdum purpurascente. Generationum successivarum divisio alternatim ad directiones 

 tres. 



Syn. — Protococcus, Ag. et Ktz., &c., ex parte. Pleurococcus, Menqh. 

 Olohulinse et Protosphaerise, Turpin, ex part. 

 Cells globose, oval, or from mutual pressure more or less angular, solitary, or consociated in free 

 families (not involved in a maternal vesicle) ; Cytioderm achromatic, homogeneous, often confluent 

 into a more or less firm mucus; cytioplasm seruglnous or pale bluish-green, not rarely yellowish or 

 orange, sometimes purplish. Successive generations arising by alternate division in three directions. 



C. refractus, Wood. 



C. cellulis in famiiias solidas arete consociatis, plerumque subquadratis, ssepius triangularibus, 

 rare angulosis; familiis saepius lobatis; cytiodermate tenui, vix visibile, achroo; cytioplas- 

 mate subtiliter granulato, subfusco vel subluteo vel ollvaceo, valde refrangente. 



Diam.— Cell ^sW— twists"- rare in cellulis singulis ^^jW; famll. tsVtt"— itt"- 

 Syn. — G. refractus, Wood, Prodromus, Proc. Amer. Philos. Soc, 1869, 122. 

 Hob. — In rupibus irroratis prope Philadelphia. 



Cells closely associated together into solid families, mostly subquadrate, very often triangular, 

 rarely multiangular ; families often lobed ; cytioderm thin, scarcely perceptible, transparent ; 

 cytioplasm finely granular, brownish, olivaceous, or yellowish, highly refractive. 



BemarJcs. — The color of this species varies from a marked almost fuscous brown 

 to a light yellowish-brown, the lighter tints being the most common. The cells 

 are remarkable for their powerful refraction of the light, resembling often oil as 

 seen under the microscope, especially if they be the least out of the focus. They 

 are very closely joined together to form the families, many of which are composed 

 only of four cells. Often, however, a large number of the cells are fused together 

 into a large, irregular, more or less lobate family, and these sometimes are closely 

 joined together into great irregular masses. I have occasionally seen large single 

 cells with very thick coats, whose protoplasm was evidently undergoing division. 

 Are such a sort of resting spore 1 The color of the protoplasm varies. Perhaps the 

 more common hue is a sort of clay tint. Bluish-olive and a very faint yellowish- 

 brown are not rarely seen. The species grows abundantly on the wet rocks along 

 the Reading Railroad between Manayunk and the Flat Rock tunnel. 



Fig. 5, pi. 5, represents different forms of this species; those marked a, magnified 

 750 diameters; b, 470 diameters; c, 950 diameters, 



€. mnlticoloratus, Wood. 



C. in strato mucoso inter algas varias sparsus ; cellulis singulis et sphsericis, vel 2-4 (rare 8) aut 

 angulis aut semisphaericis aut abnormibus in famiiias oblongas consociatis ; cytiodermate crasso, 

 hyalino, baud lamelloso; tegumentis plerumque nullis, interdum subnuUis; cytioplasmate ple- 

 rumque homogeneo, interdum subtiliter granulato, vel luteo-viride vel ceeruleo-viride vel luteo 

 vel subnigro, vel brunneo, vel saturate aurantiaco, ssepe ostro tincto. 



JXam.— Cell, sing, sine tegm., -ssW cum teg. tettt" ; cell, in famil. sing. i-sW'—fE%-e-" 

 Earn. long. „V/'_^|^j"; lat. j/^^''-^/^/'. 



