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PEL 



having a triangular auricle on each 

 side of the umbones. Hinge tooth- 

 less ; pit trigonal. One muscular 

 impression. Fossil pectens are 

 found in the neighbourhood of 

 Paris, and in many parts of Eng- 

 land ; in the Harwich cliff; in the 

 green-sand of "Wiltshire; near 

 Thame in Oxfordshire ; in Glouces- 

 tershire ; and in Sussex. 



PEBBLE. j A roundish stone of 



PEBBLE STONE. ) any kind from the 

 size of a small nut to that of a 

 man's head. A general term for 

 water-worn minerals. A mineral 

 distinguished from a flint by its 

 variety of colours. 



PE'CTINATE. | (from pecten, a comb, 



PE'CTINATED. j Lat.) 



1. In conchology, resembling a 

 comb ; cut into regular, straight 

 segments like a comb. 



2. In botany, applied to a pinna- 

 tifid leaf, whose segments are 

 extremely narrow, resembling the 

 teeth of a comb. 



PECTINIBRANCHIA'TA. The sixth or- 

 der of mollusca, in Cuvier's arrange- 

 ment. 



PE'CTOLTTE. A mineral, a silicate of 

 lime and soda. 



PECTTJ'NCULITS. A genus of orbicular 

 sub-equilateral marine bivalves, 

 with an arched hinge ; numerous 

 teeth, alternately inserted in a 

 single row; of the family Arcadidoa. 

 Pectunculi are easily recognized by 

 their rounded or lenticular form. 

 Muscular impressions two, and 

 strongly marked. Recent pectun- 

 culi are found at depths varying 

 from five to seventeen fathoms, in 

 sandy mud and sands. Fossil pec- 

 tunculi are met with in the London 

 clay and calcaire grossier, and in 

 the Bognor sandstone. 



PE'DATE. (pedatm, Lat. frompes, a 

 foot.) In botany, applied to leaves 

 in which a bifid petiole connects 

 several leaflets on the inside only ; 

 also to a peculiar kind of ternate 

 leaf, its lateral leaflet being com- 



pounded in the fore part : the black 

 hellebore is an example. 



PE'DICEL. In botany, a partial flow- 

 er-stalk, or a subdivision of the 

 general one, each subdivision being 

 termed a pedicel. 



PEDIPA'LPI. The second family of 

 Arachnidans. They have very 

 large palpi terminated by a forceps 

 or claw. The principal animals 

 among the pedipalps are the scor- 

 pions, possessing powerful organs 

 for seizing their prey, and having 

 a tail terminating in a deadly sting. 

 The other pedipalps are not armed 

 with a sting. 



PE'DUM. (pedum, Lat. a shepherd's 

 crook.) A genus of marine bival- 

 vular shells, found attached by a 

 byssus to rocks. It is an eared 

 inequivalved bivalve, gaping at the 

 lower valve, and having its beaks 

 separated : hinge toothless ; liga- 

 ment exterior; inferior notch 

 grooved. 



PE'DUNCLE. (pedunculus, Lat. from 

 pedo, a splay foot.) 



1. In botany, the stalk that bears 

 the flower and fruit. 



2. In conchology, a sort of stem 

 by which the shells of the second 

 division of lepas are attached to 

 wood, &c. 



PEDTJ'NCULATE. } Attached to objects 



PEDlfNCULATED. ) SUCh as WOod, 



rocks, &c., by a peduncle; having 

 a peduncle. 



PE'GMATITE. A name given by the 

 French mineralogists to a variety 

 of granite composed of granular 

 quartz and felspar. When in 

 granite, the mica disappears, and 

 only quartz and feldspar are left, 

 we have Pegmatite, or Graphic 

 Granite. 



PELA'GIAN. ) (pelagus, Lat. the sea.) 



PELA'GIC. j Belonging to the sea. 

 Lyell says, "belonging to the deep 

 sea." 



PELA'GIAN FOBMATIONS. Oceanic accu- 

 mulations ; deposits by currents, or 



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