Wood.] ^-^"^ [June 18. 



After all, in many instances it appears impossible to clean these algae 

 without utterly ruining and destroying them — the dirt often seeming to 

 be almost an integrant portion of them ; so that he who despises and rejects 

 mounted specimens, simply because they are dirty and unsightly, will 

 often reject that which, scientifically speaking, is most valuable and 

 attractive. 



In concluding this introduction, it is perhaps pardonable to state, that 

 there are in my possession elaborate descriptions and drawings (from 

 nature) of nearly all the plants mentioned in this paper, and that of the 

 species mentioned, all but a dozen or two are new to science or new to 

 this continent. 



CLASS PHYCOCHROMOPHYCEAE. 



ORD. CYSTIPHORAE. 

 FAM. CHROOCOCCACEAE. 



GEN. CHROOCOCCUS. 



C. REPRACTUS. 8p. NoV. 



C. cellulis in familias solidas arete consociatis, plerumque subquad- 

 latis, saepius triangularibus, rare multiangulis ; familiis saepius loba- 

 tis ; cytiodermate tenui, vix visibile, achroo ; cytioplasmate subiliter 

 granulato, subfusco vel subluteo, valde refrangente. 



C. Cells closely associated together into solid families, mostly sub- 

 quadrate, very often triangular, rarely multiangular ; families often 

 lobed ; cytioderm thin, scarcely perceptible, transparent ; cytioplasni 

 finely granular, brownish or yellowish, highly refractive. 



Diam. ceW-^-^^-^" goVo"? '^^^'^ "^ cellulis singulis 20V0" 5 famil. x-joo" 



170 • 



Hab, In rupibus irroratis prope Philadelphia. 



C. MTJLTICOLORATUS. 8p. NoV. 



C. in strato mucoso inter algas varias sparsus ; cellulis singulis sphae- 

 ricis, vel 2-4 (rare 8) aut angulis aut semisphaericis aut abnormibus in 

 familias oblongas consociatis ; cytiodermate crasso, hyalino, hand lamel- 

 loso ; tegumentis plerumque nullis, iuterdum subnuUis ; cytioplasmate 

 plerumque homogeneo, interdum subiliter granulato, vel luteo-viride 

 vel caeruleo-viride vel luteo vel subnigro, vel brunneo, vel saturate 

 aurantiaco, saepe ostro tincto. 

 Diam. cell., sing, sine tegm., gVijo'' <^^™ teg. 15^0" ; cell, in famil. sing. 



2 // i II "PnTTi Inner -" " 10_// . lo+ fi // T // 



C. Occurring scattered in a mucous stratum with other algae ; cells 

 spherical and single, or else angular semisphaerical or irregular and asso- 

 ciated together in oblong families of from 2-4 -(rarely 8) ; inner coat thick, 

 hyaline, not lamellate ; outer coat generally wanting, sometimes indis- 

 tinctly present ; endochrome mostly homogeneous, sometimes minutely 



