FRESU-WATER ALG^ OF THE UNITED STATES. H 



Genus CHROOCOCCUS, Njegeli. 



CelluliE globosse ovales vel a pressione rautua plus minus angulosse, solitariie vcl in familias con- 

 sociatse, libersie (a vesica matricali non involute); cytiodcrmate acliromatico, horaogeneo, siepein niuco 

 plus minus finuo couliuente; cytioplasmate ffirugiuoso vcl pallide ca;ruleo-viridi, non rare luteolo vel 

 aurantiaco, iuterdum purpurascente. Generationum successivarum divisio alternatim ad directiones 

 tres. 



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

 Globulinee et Protosphaeriae, 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 Ann mucus; cytioplasm a;ruginous 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 familias solidas arete consociatis, plerumque snbqnadratis, saspius triangiilaribus, 

 rare angulosis; familiis sa;pius lobatis; cytiodcrmate tcnui, vix visibile, acliroo; cytioplas- 

 mate subtiliter granulate, subfusco vel subluteo vel olivaceo, valde refrangente. 



Diam.— Cell gAir"— suVn". rare in cellulis singulis ^^Vu"; famil. ^^^-^"—^\-^". 

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

 Eab. — In rupibus irroratis grope Philadelphia. 



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

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

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



Remar'ks. — The color of this species varies from a marked almost fuscous brown 

 to a light yellowish-brown, the lighter tints being the most common. Tlie 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, irregidar, more or less lobate family, and these sometimes are closely 

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

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

 Are such a sort of resting spore ■? 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 «, magnified 

 750 diameters; h, 470 diameters; c, 950 diameters. 



C. miilticoloratiis, Wood. 



C. in strato mucoso inter algas varias sparsus ; cellulis singulis et sphocricis, vcl 2-4 (rare 8) ant 

 angulis aut semispha;ricis aut abnormibus in familias oblongas eonsociatis ; cytiodcrmate cra.s.so, 

 byalino, hand lamelloso; tegumentis plerumque nullis, interdum subnullis; cytioplasmate ple- 

 rumque homogeneo, interdum subtiliter granulato, vel luteo-viride vel creruleo-viridc vel luteo 

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



I>;am.— Cell., sing, sine tegm., 5/5^" cum teg. Tfi,^"; cell, in famil. sing, j/jru"— js^'sb-" 

 xara. long. 5555 — use t '^l. jjg^ — J505 • 



