PEA 



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PEA 



grey, and the grains or globules of 

 which the mass is composed, vary 

 from the size of mustard seed to 

 that of large peas. 



PEA GEIT. A member of the inferior 

 oolite ; a pisolitic limestone, made 

 up of flattened oval concretions 

 rather larger than peas ; it occurs 

 near Cheltenham, and attains a 

 thickness of forty feet. 



PEACH. A provincial term for either 

 chlorite or mica, if the latter have 

 a tinge of green. 



PEAE E'NCEINITE. The Apiocrinites 

 rotundus, or Bradford encrinite. A 

 species of crino'idea abounding in 

 the oolitic limestone in the neigh- 

 bourhood of Bradford, near Bath. 

 When living, their roots were con- 

 fluent, and formed a thick pavement 

 over the bottom of the sea, from 

 which their stems and branches 

 rose into a thick submarine forest, 

 composed of these splendid zoo- 

 phytes. This bed of beautiful 

 remains has been buried by a thick 

 stratum of clay. The body of the 

 pear encrinite was of a pyriform 

 shape, from which circumstance it 

 has been thus named. The pear 

 encrinite is confined to the middle 

 oolite. 



PEAEL. (perle, Germ . per k, Pr. ptrla, 

 It.) A spherical concretion con- 

 sisting of concentric coats of the 

 same substance as that which forms 

 the mother-of-pearl of the shell. 

 It is produced by the extravasation 

 of a lapidifying fluid, secreted in 

 the organs of the animal, the pearl 

 oyster, and filtered by its glands. 

 The animal that produces pearls in 

 the greatest abundance, of the 

 purest nature, and of the highest 

 value, has been formed by Lamarck 

 into a genus named Meleagrina; 

 Linne classed it with the muscles. 

 It inhabits the Persian gulf, the 

 coast of Ceylon, &c. It attains 

 perfection no where but in the 

 equatorial seas. The pearl fishery 

 off the island of Ceylon is the most 



productive of any ; the oyster-beds 

 extending over a space thirty miles 

 long by twenty-four broad. The 

 oysters at the greatest depths yield 

 the largest pearls, which are situated 

 in the fleshy part, near the hinge. 

 For one pearl that is found per- 

 fectly round and detached between 

 the membranes of the mantle, 

 hundreds of irregular ones occur 

 attached to the mother-of-pearl; 

 these are sometimes in such numbers 

 as to prevent the animal from closing 

 its valves, and thereby cause its 

 destruction. 



The pearl is supposed by some 

 writers to be the effect of disease ; 

 it is a formation forced upon the 

 oyster by some extraneous sub- 

 stance within the shell, which it 

 covers with mother-of-pearl. Sir 

 Everard Home considered that the 

 abortive eggs of the animal were 

 the nuclei upon which the pearls 

 were formed. 



To collect the pearl oysters, 

 divers are employed; these men, 

 provided with baskets, descend to 

 the bed at the bottom of the sea, 

 and during their stay there, which 

 does not exceed two minutes, gener- 

 ally a minute and a- half, collect 

 into their baskets every thing they 

 can grasp, when they are rapidly, 

 at a signal given, hauled up to the 

 surface. When the bed is richly 

 stored, a diver will collect 150 

 oysters at one dip, and a single 

 diver will, in one day, bring up 

 from 1000 to 4000 oysters. Kirby. 



PEAEL SI'NTEE. Called also fiorite. 

 A variety of silicious sinter of a 

 white or grey colour, found in vol- 

 canic tuff. 



PEA'ELSTONE. An igneous or volcanic 

 rock with a mother-of-pearl lustre. 

 The Perlstein of Werner ; Obsidi- 

 enne perlee of Brongniart; Lave 

 vitreuse perlee of Haiiy. Pearl- 

 stone is a variety of obsidian, occur- 

 ring in globular and concentric 

 lamellar, irridescent, translucent 



