PAR 



PEA 



upper marine marls and limestones. 5. 

 Third fresh-water formation ; containing 

 siliceous millstone without shells, siliceous 

 millstone with shells, and upper fresh- 

 water marls. Subsequent observations 

 have proved that this division, as well as 

 many of the views entertained by MM. 

 Brongniart and Cuvier, is not in accord- 

 ance with facts with which they were un- 

 acquainted, and much modification of the 

 above arrangement has been the conse- 

 quence. The siliceous limestone, with 

 fresh-water and terrestrial shells and 

 plants, and the calcaire grossier, or first 

 marine formation, often alternate, and 

 are deemed by M. Constant. Prevost to 

 be contemporaneous formations ; and it 

 is not improbable that while the waters 

 in one lake or basin might be marine, 

 those in another might be fresh, and thus 

 two formations containing different or- 

 ganic remains might be deposited con- 

 temporaneously. LyelL Bakewell. 



PA'RTICLES ELEME'NTARY. The final re- 

 sults of chemical analysis. Elementary 

 particles are those of which integrant 

 particles are composed ; thus, while the 

 latter remain invariable in the same body, 

 the former must vary with the progress 

 of chemistry. In bodies really simple, 

 the integrant and elementary particles 

 must be the same. Cleaveland. 



PA'RTICLES I'NTEGRANT. These are the 

 smallest particles into which a body can 

 be reduced without destroying its nature, 

 or, in other words, without decomposing 

 it. Only three forms of integrant par- 

 ticles have hitherto been discovered. 

 They are the three most simple, geome- 

 trical solids ; namely, a tetraedron ; a tri- 

 angular prism ; and a parallelepiped, in- 

 cluding all solids of six sides, parallel 

 two and two. 



PA'RTITE. (partitus, Lat. from partior, to 

 divide.) Divided. In botany, a partite 

 leaf is one separated to the base. 



PATE'LLA. (j9atfe?Za, Lat. a little deep dish 

 with a broad brim.) That bone of the 

 leg commonly known as the knee-pan. 



PATE'LLA. In conchology, the limpet shell. 

 Animal a limax. A marine shell, uni- 

 valve, subconic, shaped like a basin ; 

 without a spire. In Turton's Linne two 

 hundred and forty species of patella, or 

 limpets, are described : fourteen of these 

 are inhabitants of our coasts. The patella 

 is found both recent and fossil. Recent 

 patellae are found at depths varying to 

 thirty fathoms, on rocky coasts, stones, 

 and sea- weeds. Many species have been 

 found" fossil in the neighbourhood of 

 Paris. Patellae have also been obtained 

 from the Shanklin sand, and from the 

 Harwich cliffs. Mr. Parkinson mentions 

 that he possesses a fossil patella of the 



species P. ungarica, of the size of two 

 inches and a-half in its longest diameter. 



PATE'LLIFORM. (from patella, a dish, and 

 forma, form, Lat.) Of the form of a 

 small dish. 



PATE'LLITE. A fossil patella. 



PA'TULOUS. (patulus, from pateo, Lat. to 

 be open.) In botany, spreading, as a 

 patulous calyx. In conchology, gaping ; 

 with a spreading aperture. 



PAVO'NIA. (from pavo, Lat. a peacock.) 

 A coral with a deep and isolated cell, 

 such cell containing a large depressed 

 polypus, very similar to the actinia as 

 regards both its structure and appearance. 

 In Dr. Mantell's Wonders of Geology a 

 species of pavouia, the P. lactuca, is beau- 

 tifully figured. He states that the polypi 

 are of a deep green colour, and that there 

 is a connecting, transparent, fleshy sub- 

 stance, which extends over the extreme 

 edges of the foliated expansion of this 

 elegant coral. 



PEA ORE. The name given to granular 

 argillaceous oxide of iron, from its occur- 

 ring in small masses or grains, nearly or 

 quite spherical, and of the size of a pea. 

 It is the pisiform iron-stone of Kirwan. 



PEAR E'NCRINITE. The Apiocrinites ro- 

 tundus, or Bradford ecrinite. A species 

 of crinoidea abounding in the oolitic lime- 

 stone in the neighbourhood of Bradford, 

 near Bath. When living, their roots were 

 confluent, 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 zoophytes. This bed of beauti- 

 ful remains has been buried by a thick 

 stratum of clay. The body of the pear 

 ecrinite was of a pyriform shape, from 

 which circumstance it has been thus 

 named. The pear ecrinite is confined to 

 the middle oolite. 



PEARL, (perle, Germ, perle, Fr. perla, It.) 

 A spherical concretion consisting of con- 

 centric 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 abun- 

 dance, 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 coasts 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 



