USED IN NATURAL HISTORY. 



119 



PITC'ITART. fr. }at.pituita, phlegm. 

 The lining membrane of the nose 

 is called the pituitary membrane. 



PITU'ITOUS. Discharging mucus. 



PLACE' XTA. Lat. A cake. The 

 organ by which the embryo of 

 mammals is attached to its mo- 

 ther. In botany, that part of the 

 ovary from which the ovules 

 arise. 



PLACOIDEANS. fr. gr. plax, a broad 

 plate; eidos, resemblance. An or- 

 der of fishes, (p. 48, Book viii). 



PLACU'NEA. Lat. fr. gr. plakoeis, 

 broad, flat, even. A bivalve mol- 

 lusk. 



PLAGIH2BDRAL. fr. gr. plagWS, ob- 



lique ; Wra, a side. Having ob- 

 lique faces ; applied to crystals. 



PLAGIO'STOMA. fr. gr. plagios, ob- 

 lique ; stoma, mouth. A genus of 

 bivalve tnollusks. 



I'LANO'RBIS. fr. lat. planus, flat ; or- 

 bis, a circle. A genus of marsh 

 snails, (fig. 29, p. 42, Book v). 



PLAXO-COMPRKSSED. Compressed 



down to a flattish surface. 



PLAWTIGRA'DA. Plantigrade ani- 

 mals. 



PLANTIGRADE. fr. lat planta, the 

 sole of tlie foot; gradi, to walk. 

 Applied to certain mamrniferous 

 animals that, in walking, rest the 

 entire sole upon the ground. 



PLA'NTULE. A diminutive plant. 



PLA'NUS. Lat. Flat. 



PLASTER OF PARIS. A substance 

 prepared by heating gypsum. 



PLASTIC CLAY. Potters' clay. (p. 

 78, Book viii). 



PLAS'TRUM. The inferior shell of a 

 tortoise. 



PLATALE'A. fr. gr. platus, flat. The 

 generic name of the spoonbills. 



PLA'TEAIT. Fr. An elevated plane, 

 or table land. 



PLA'TEAUX. fr. plur. of plateau. 



PLATES'SA. fr. gr. platus, broad, flat. 

 Systematic name of the plaice. 



PLA'TIJTA 01 PLA'TINUM. fr. sp.pla- 

 fa, silver, on account of its colour. 

 A metal of a whitish colour, ex- 



ceedingly ductile, malleable, and 

 of difficult fusion. 



PLA'TURUS. Generic name of cer- 

 tain ophidians. 



PLATTSO'MUS. fr. gr. platus, flat ; 

 soma, a body. A genus of fos- 

 sil fishes, (fig. 57, p. 48, Book 

 viii). 



PLECTO'GNATHI. fr. gr. phktos, 



twined, joined together; gnathos, 

 jaw, cheek. Systematic name of 

 an order of fishes. 



PLEIO'CEUE. 7 fr- gr. pleion, more ; 



PLIO'CEBTE. 3 kainos, recent. A 

 term applied by geologists to the 

 newer tertiary formation, because 

 there is found fossilized in it a 

 greater number of existing than 

 of extinct species, (pp. 78, 89, 

 Book viii). 



PLESIOSAU'RUS. fr. gr.pleisot, most; 

 saura, a lizard. The systematic 

 name of a fossil saurian, (p. 57, 

 Book viii). 



PLEIS'TOCENE. fr. gr. pleistos, the 

 most; kainos, recent. The newer 

 pliocene formation, or newest ter- 

 tiary. 



PLETJRE'NCHYMA. fr. gr. pleura, the 

 side; egchunia, infusion. The 

 woody tissue of plants. 



PLEUROBRA'ifCHi.-Lat. plur. of pleu- 

 robranchus. 



PLEUHOBRA'ircHrs. fr. gr. pleura, 

 side ; bragchia, gills. A genus of 

 gasteropods. (p. 63, Book v). 



PLEUROITE'CTES. fr. gr. pleura, the 

 side; nectes, fin. Systematic name 

 of a family of fishes : the floun- 

 der tribe. 



PLEURO'TOMA. fr. gr. pleura, side ; 

 tome, a notch. A genus of uni- 

 valve mollusks, having a notch 

 in the side of the shell, (fig. 116, 

 p. 94, Book v). 



PLEUROTOMA'RIA. A tribe of mol- 

 lusks. 



PLI'CA. -Lat. A fold. 



PLI'CATE. fr. lat. plicatus, plaited. 

 Folded like a fan. Folded or 

 plaited, as in the pillar of the vo- 

 lute tribe. 



