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four species. Phyllade is largely 

 found in Cornwall and Devon. The 

 rocks comprised in this genus con- 

 sist in great measure of very thick 

 beds, which are closely lamellar, 

 and even compact and jointed, like 

 the felspar rocks ; indeed, they 

 seem to be principally composed of 

 felspar, the most compact and sili- 

 cious becoming weathered on ex- 

 posure to the atmosphere. Phyllade 

 differs from corneanite in having a 

 granular instead of a compact basis, 

 and it always contains minute 

 spangles, like scales of mica. 



PHY'SALITE. A variety of prismatic 

 topaz, of a greenish-white colour. 

 It occurs in coarse granular con- 

 cretions, having a low degree of 

 lustre. Edges feebly translucent. 

 It consists of alumina 57*75, silica 

 34-30, fluoric acid 7'81. 



PHY'LLITE. (from 0vX\oj/, a leaf, and 

 7u'0os, a stone, Gr.) A petrified 

 leaf. 



PHYLLO'PHAGOTTS. An animal that 

 feeds on leaves ; the silk-worm is 

 an example. 



PHYLLOLE'PIS. The name assigned 

 to a genus of ichthyolites of the 

 old red sandstone. 



PHY'SICAL. (physique, Fr. fisico, It.) 

 Relating to nature or to natural 

 philosophy ; not moral ; pertaining 

 to material things. 



PHY'SICS. (from 0tW, nature, Gr.) 

 Taken in its most enlarged sense, 

 comprehends the whole study of 

 nature ; but in the usual accepta- 

 tion of the word, that branch of 

 science which treats of the proper- 

 ties of natural bodies, and includes 

 natural history and philosophy. 



PHYTI'VOEOUS. (from 0vroi/, Gr. a 

 plant, and voro, Lat. to devour.) 

 Feeding on plants. 



PHY'TOLITE. (from 0tn-oj/, a plant, 

 and X/005, a stone, Gr.) A petri- 

 fied or fossilized plant. 



PHYTO'LOGY. (from 0vroi/, a plant, 

 and Xo'ryos, discourse, Gr.) That 

 department of science which treats 



of the nature, habits, qualities, &c., 

 of plants. 



PHYTO'PHAGOUS. (from 0m-oi/, a plant, 

 and 0a<yetV, to eat, Gr.) Feeding 

 on plants; devouring plants ; feed- 

 ing on vegetable substances. 



PHYTOSAT/RUS. A fossil saurian dis- 

 covered in the saliferous formation, 

 and thus named by Jaeger. 



PHYTOZO'A. (from 0vroi/, a plant, 

 and %wov, an animal, Gr.) Plant- 

 like animals. Another, and more 

 modern, as well as appropriate 

 name for zoophytes. 



PI'CROSMLNE. A silicate of magnesia, 

 having nearly the same composition 

 as serpentine. 



PIGME'NTTTM NI'GRUM. A dark brown, 

 or nearly black substance, which 

 covers the surfaces of the choroid 

 membrane of the eye, and gives to 

 it its colour. 



PI'LETJS. The name given to a genus 

 of fossil echini ; pileus is another 

 name for conulus. 



PI'LLAR. In conchology, the colum- 

 ella, or perpendicular centre, 

 which extends from the base to 

 the apex, in most of the spiral 

 shells. 



PI'LLAR- LIP. In conchology, a conti- 

 nuation of the glossy process with 

 which the aperture of shells is 

 lined, expanded on the columella. 



PI/LOSE, (pilosus, Lat.) In entomo- 

 logy, covered with dispersed, long, 

 and bent hairs. 



PI'MELITE. A variety of steatite, 

 coloured by chrome or nickel. 



PI'NEAL GLAND, (frompineus, Lat. a 

 pine.) The name given to a gland 

 of the brain from its supposed re- 

 semblance to a pine. This gland 

 was at one time supposed to be the 

 seat of the soul. 



PI'NNA. (pinna, Lat. the fin of a 

 fish.) A genus of marine bivalves, 

 belonging to the family Mytilacea. 

 A cuneiform, longitudinal bivalve, 

 with an acute base, the upper part 

 gaping; hinge without a tooth, 

 lateral, and very long ; valves co- 

 z z 



