PED 



PEL 



PECTIN [irmrh, a coagulum). The 

 name given by Braconnot to a principle 

 which forms the basis of vegetable jelly. 



PE'CTINATE (pecten, a comb). In 

 Botany, a term expressing a modification 

 of the pinnatifid leaf, in which the seg- 

 ments are long, close, and narrow, like 

 the teeth of a comb. 



PE'CTINATED (pecten, a comb). 

 Having processes resembling in form and 

 arrangement the teeth of a comb, as the 

 spines of some species of murex. 



PE'CTINIBRANCHIA'TA(pec^ew,pec- 

 tinis, a comb, hranchice, gills). The name 

 of the sixth, the most highly organized 

 and the most numerous order of Gastero- 

 pods, including all the inhabitants of 

 spiral univalve sea-shells, and many with 

 shells simply conical, which have their 

 comb-shaped gills placed internally in a 

 capacious cavity, into which the water is 

 freely admitted. 



PECTI'NID-^. A tribe of Monomy- 

 arian conchifers, including the pectens, 

 the limae, the oysters, &c. 



PECTORA'LES PEDU'NCULATI. A 

 family of Acanthopterygious fishes, in 

 which the pectoral fins are attached to 

 the bones by a peduncle, resembling a 

 wrist, enabling the fish to leap in pursuit 

 of its prey, as in the lophius, or fishing- 

 frog. 



PE'DAL {pes, pedis, a foot). A foot- 

 key in musical instruments, or a lever 

 for acting on the swell of the organ or 

 the piano-forte. A pedal-base is a base 

 which remains stationary on one note, 

 while the other parts continue to move 

 and form various chords which are re- 

 lated to the pedal-base according to the 

 laws of harmony. 



PED ATE. A botanical designation of 

 that form of the palmate leaf, in which 

 the two lateral lobes are themselves sub- 

 divided, as in helleborus niger. The 

 same modifications occur as in the pal- 

 mate leaf, with similar terms, as peda- 

 tifid, pedatipartite, pedatisected, and pe- 

 datilobate. 



PEDICELLA'RIiE {pedicellus, a little 

 stalk). The name of certain appendages 

 to the integument of the Echini and 

 other echinodermata, consisting of a 

 dilated end or head, usually prehensile, 

 supported by a slender stem or pedicel. 

 They have been distinguished by Valen- 

 tin into the gemmiform, the tridactyle, 

 and the snake-headed, or ophicephalous. 



PEDIPA'LPI (pes, pedis, a foot, palpi, 

 the organs of touch in insects). A divi- 

 sion of the Arachnida, in which the 

 251 



palpi are exceedingly strong, and fur- 

 nished at their extremity with a prehen- 

 sile forceps, as in the scorpion, 



PEDO'METER (nedov, the ground, 

 /ierpoi/, a measure). An instrument 

 for measuring the distance which a person 

 has performed by walking or riding. It 

 is of a portable size, and its operation 

 is eflfected by motion communicated to 

 its machinery by the traveller him- 

 self. 



PE'DUNCLE and PE'DICEL, In 

 botanical language, the peduncle is that 

 part of the inflorescence which proceeds 

 immediately from the stem. If it is 

 divided, its principal divisions are called 

 branches ; and its ultimate ramifications, 

 which bear the flowers, are named pedi- 

 cels. There are modifications of the 

 peduncle, to which other names are ap- 

 plied. See Rachis and Scape. 



PEDU'NCULATE (pedunculus, a. foot- 

 stalk). That which is supported on a 

 peduncle, or foot-stalk, as the shell of 

 Terehratula, or a flower furnished with a 

 stalk. See Sessile. 



PE'GASUS. The Flying Horse ; one 

 of the old northern constellations, con- 

 sisting of eighty-nine stars. 



PE'GMATITE. A granular mixture 

 of quartz and felspar. It often occurs 

 in granite veins and passes into Graphic 

 Granite, from which some geologists do 

 not distinguish it. 



PELECA'NIDiE. The Pelican tribe ; 

 a family of the Natatores, or Swimming 

 birds, characterized by having the hind 

 toe united by membrane to the rest. 

 They are, nevertheless, almost the only 

 birds of the order which perch upon 

 trees. They include the pelican, the 

 cormorant, the frigate-bird, the gannet, 

 and the boobie. 



PELIO'MA. lolite. A blue-coloured 

 mineral, belonging to the garnet tribe, 

 now commonly called dichroite, from its 

 exhibiting two different colours when 

 viewed in different positions. 



PELLICLE (dim. of pellis, the skin 

 or hide of a beast, flayed off"). A thin 

 skin, or film. Among chemists, it de- 

 notes a thin surface of crystals uniformly 

 spread over a saline liquor evaporated to 

 a certain degree. 



PE'LOKONITE. An amorphous mi- 

 neral, of a bluish-black colour, contain- 

 ing phosphoric acid, iron, manganese, 

 and copper. 



PE'LTATE (pelta, a shield). Shield- 

 shaped; a term applied by botanists to 

 leaves which are fixed to the petiole by 

 M6 



