PLATYGRAMMA. 



PLEUROXUS. 



PLATYGRAMMA, Meyer. A genus of 

 Graphideae (Gymnocarpous Lichens), con- 

 taining two British species. 



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

 xiii. p. 393. 



PLATYZOMA, R. Brown. A genus of 

 Gleichenaeous Ferns. Exotic. 



PLEOPELTIS, Humb. and Bonpl. An 

 exotic genus of Polypeae, remarkable for the 



Fig. 591. 



Fig. 592. 



Pleopeltis nuda. 



Fig. 591. A sorus seen from above. 



Fig. 592. Vertical section of ditto. 



Magnified 25 diameters. 



presence of peculiarly 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 

 Diatomaceae, 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 

 Taenitideae (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. 66). Aquatic. 



P. marina, D. Has the body somewhat 



narrower than the last, and is pointed in 

 front. Marine. 



BIBL. Dujardin, In/us, p. 473. 



PLEUROPYXIS, Corda. A genus of 

 Antennarei (Physomycetous Fungi), growing 



Fig. 593. 



Plcuropyxis 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 (=zHydatina with uniden- 

 tate jaws). 



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

 oblong, truncate in front; toes small, turgid. 

 Aquatic ; length 1-216". 



Other species. 



BIBL. Ehrenberg, In/us, p. 418; Gosse, 

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



PLEUROXUS, Baird. A genus of En- 

 tomostraca, of the order Cladocera, and 

 family Lynceidae. 



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 



