PLATYGRAMMA. 



[ 512 ] 



PLEUROXUS. 



PLATYGRAMMA, Meyer.— A genus of 

 Graphideae (Gymnocarpous Lichens), con- 

 taining two British species. 



BiBL. Leighton, Ann. Nat. Hist. 2 ser. 

 xiii. p. 3.93. 



PLATYZOMA, R. Brown.— A genus of 

 Gleichenseous Ferns. Exotic. 



PLEOPELTIS, Hmnb. and Bonpl.— An 

 exotic genus of Polypes, remarkable for the 



Fig. 5.9L 



Fig. 592. 



Pleopeltis nuda. 



Fig. 591. A sorus seen from above. 

 Fig. 592. Vertical section of ditto. 



Magnified 25 diameters. 



presence of pecuharly formed so-called para- 

 physes in the sori. These bodies are peltate, 

 or like minute flat mushrooms or umbrellas 

 expanded over and sheltering the sporanges 

 (figs. 591,592). 



PLEUROCOCCUS, Menegh.— A form 

 of Protococcus. 



PLEURODESMIUM, Kg.— A genus of 

 Diatom aceae, allied to Striatella, but the 

 characters given are very obscure. Marine. 

 Africa. 



BiBL. Kiitzing, Bot. Zeit. 1846. p. 248; 

 Sp. Alg. p. 115. 



PLEUROGRAMMA, Presl.— A genus of 

 Tffinitideae (Polypodaeous Ferns). Exotic. 



PLEURONEMA, Duj.— A genus of In- 

 fusoria, of the family Paramecina. 



Char. Body oblong-oval, depressed, with 

 a broad lateral orifice, from which a bundle 

 of long, curved, floating and contractile 

 ciliary filaments issues. 



P. chrysalis [crassa], D. = Paramecium 

 chrysalis, E. (PI. 24. fig. ^Q). Aquatic. 



P. marina, D. Has the bodv somewhat 



narrower than the last, and is pointed in 

 front. Marine. 



BiBL. Dujardin, Infiis. p. 473. 



PLEURO'PYXIS, Corda.— A genus of 

 Antennarei (Physomycetous Fungi), growing 



Fig. 593. 



Pleuropyxis microsperma. 

 Magnified 200 diameters. 



upon leaves and stems. This and Pisomyx a 

 are stated by mistake, under Antennarei, 

 to be British (fig. 593). 



BiBL. Corda, Icon. Fung. pi. 6. fig. 291. 



PLEUROSIGMA, Smith. See Gyro- 



SIGMA. 



PLEUROTROCHA, Ehr.— A genus of 

 Rotatoria, of the family Hydatinaea. 



Char. Eyes none ; a single tooth in each 

 jaw : foot forked {=Hydatina with uniden- 

 tate jaws). 



P. gibba (PL 35. fig. 18). Body ovate- 

 oblong, truncate in front; toes small, turgid. 

 Aquatic; length 1-216". 



Other species. 



BiBL. Ehrenberg, Jw/m5. p. 418; Gosse, 

 Ann. Nat. Hist. 1851. viii. 199. 



PLEUROXUS, Baird.— A genus of En- 

 tomostraca, of the order Cladocera, and 

 family Lynceidse. 



Char. Anterior part of shell prominent 

 above, obliquely truncate below ; first pair 

 of legs very large ; beak sharp, curved 

 downwards. Aquatic. 



P. trigonellus (PI. 14. fig. 32). Beak 

 long, sharp-pointed, slightly curved down- 

 wards ; inferior antennae short and slender, 

 anterior branch with four setae, one from the 

 first joint, one from the second, and two 

 from the last ; posterior branch with three 

 setae all arising from the last joint. 



P. uncinatus. Beak curved upwards at 

 the end ; three sharp spines at the anterior 

 inferior angle of the shell ; inferior antennae 

 as the last. 



P. hamatus. Beak blunt and strong, 

 slightly curved downwards; first pair of legs 



