1869.] 123 [Wood. 



granular, either a yellowish green or bluish green, or yellowish, or brown, 

 or blackish, sometimes tinged with bright lake. 

 Hab. In rupibus humidis prope Philadelphia. 



GEN. GLOEOCAPSA. 



G. SPARSA. Sp. Nov. 



G. in strato mucoso sociis algis variis sparsa ; cellulis sphaericis, vel 

 oblongis vel ovatis, 2-8 in familias consociatis ; familiis subglobosis vel 

 subovatis, interdum numeroso-aggregatis ; tegumentis internis aureo- 

 fuscis, firmis, rarissime coloris expertibus, homogeneis, vel lamellosis ; 

 tegumentis externis achromaticis, rare subachromaticis, plerumque vix 

 visibilibus; cytioplasmate homogeneo. 



Diam. max. cell, oblong, sine tegum. long., g^Vff" 5 l^t-» j-soo" ! cell, 

 glob., sine tegum., ^^l^^// ; cum tegum., ^sV^" ; fam., ^i^". 



G. scattered in a mucous stratum composed of various algae ; cells 

 spherical, or oblong, or ovate, associated together in families of from 

 2-8 ; families subglobose or subovate, sometimes aggregated together 

 in large numbers; inner tegument yellowish brown, firm, rarely colorless, 

 homogeneous or lamellate ; external tegument achromatic, rarely sub- 

 achromatic, generally scarcely visible. 



GEN. MERISMOPEDIA. 



M. CONVOLUTA. Bv^b. 



Hab. Prope Philadelphia. 



Remarks. — I have only a slide of specimens, which were given me by my 

 friend Dr. J. Gibbons Hunt. Our American form seems to be too close to 

 the European species to be separated from it, although in no case is 

 the frond in any wise plicate or convolute, and the cells are somewhat 

 smaller (long diameter, eAo")- 



M. NOVA. Sp. Nov. 



M. thallo membranaceo, distincte limitato, cellulis numerosissimis 

 composito ; cellulis ovalibus, arete approximatis, 16 in familias consoci- 

 atis, dilute caeruleo-viridibus, interdum medio constrictis; thalli margini- 

 bus rectis, integris . 



Thallus membranaceous, distinctly limited, composed of very numer- 

 ous cells ; cells oval, closely approximated, consociate in families of 16, 

 light bluish green, sometimes constricted in the middle ; margin of the 

 thallus straight and entire. 



Diam. cell. ad. -^-so^". 



Hab. In flumine Schuylkill, prope Philadelphia. 



FAM. OSCILLARIACEAE. 



GEN. OSCILLATORIA. 

 o. NIGRA. Vatich. 

 In stagnis prope Philadelphia. 



