PLECANIUM. 



[ 606 ] 



PLEUKOSIGMA. 



TLEC A 'XI UM, Reuss.— Texfuktrlce with 

 sandy sliell-titsue rome under this lieadiuo:. 



BiBL. Reus?, Sifziim/sh. Wien, xliv. 38-3. 



PLEOPEL'TIS, Hu'mb. ;ind BoDpl.— An 

 exotic genus of Polypodiefe (Polypodioid 

 Ferns), remarkable for the presence of 

 peculiarly formed so-called paraphyses in 

 the sori, performino- the function of an 

 indusium. These bodies are peltate, or 

 like minute fiat mushrooms or umbrellas 

 exptinded over and sheltering the spurauges 

 (ligs. 586, 587). 



Fio-. 586. 



Fig. 587. 



Pleope)tis nuda. 



Fig. 58i5. A sorus, seen from above. 



Fig. 587. Vertical section of ditto. 



Magnified 2.5 diameters. 



-Mosses vrith late- 



A genus 



PEEUROCAR'PI. 



ral fruits. 



PEErROCAR'PUS, Braun 

 of Zygnemace* (Confervoid ALie) 



2 .-species, in freshwater pools. (Rabenh. 

 Alq.m. 258.) 



■PLEURUCLA'DIA, Braun.— A genus 

 of Fucoiden?-, group Plifcosporepe. P. In- 

 ciifU-is: freshwater, (llnheuh.. Alg . iii. 393.) 



PEEUROCOC'CUS, IMeneg.— A genua 

 of Pfflraellacefe ( Uni cellular Algae). 



Clt'ir. Cells single or collected in glo- 

 bular or cubical masses, globular or angular 

 from pre-ssure, with a central nucleus ; 

 cytioderni thick and hyaline; cell-contents 

 homogi'neou*, green or reddish. Multipli- 

 cation by Jiltemate fission in opposite direc- 

 tions. G(;nidia formed, in special cells. 

 Thev present the greatest similarity to the 

 gonidia of I^ichens. Several species = 

 forms of Prof.ococcus ? 



Binr,. Meneg. Nosfoch. 38; KdgeW, Si/d. 

 124; Rabenh. .-!/,'/. iii 24. 



PLEURODEB'MIUM, Kiitz.— An ob- 

 scure genus of DiatoHiacea;, allied to Stria- 

 iella\ maiine; Africa. 



BiBL. Kiitz. Sp. A/q. 115. 



PLEUROM'ONAS", Perty.— A genus of 

 Flagellate Infusoria. 



Char. Reniform, extremely delicate, 

 small, colourless; flagellum single, from 

 the concave side of the body, three times 

 its length. P. jnrulans; motion jerking; 

 stasnant water. (Pertv, Lehenrf. 111.) 



PLEURONE'MA, "Duj.— A genus of 

 Holotrichous Infusoria, family Colpodina. 



Char. Body oblong-oval, dejn-essed, with 

 a broad lateral orifice, from \\ liich a bundle 

 of long, curved, floating and contiactile 

 ciliary filaments issue. 



F.' chrysalis, (crassa) D. (PI. 31. fig. 66). 

 Freshwater. Other species. 



Bir.L. Duj. Infi/s. 473; Clap, et Lach. 

 Inf. 274 : Kent, Inf. o42. 



PLEUROPH'RYS, Clap.— A genus of 

 Actinophryina (Rhizopoda). 



Char. Body invested with a sheath in- 

 crusted with extraneous siliceous particles. 

 P. sphcerica. Freshwater. 

 BiBL. Clap. etLachm./«/w6-. 454; Archer, 

 Qu. Mic. Jn. 2870. 



PLEUROPYX'IS, Cordn.— A genus of 

 Mucorini (Phycomycetous Fungi), growing 



Fig. 588. 



Pleuropyxis microsperma. 

 Magnified 200 diameters. 



upon leaves and stems. This genus is im- 

 perfectly known. 



Bibl' Coida, Icon. Fnnq. pi. 6. fig. 291. 



PLEUROSIG'MA, Smith.— A genus of 

 Diatoma( eoe. 



Char. P'rustules single, ft-ee, lorger ihau 

 broad ; front view linear or hnear-laiiceolate; 

 valves navicular, sigmoid, with a longitu- 



