PAN 



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P A 



middle branches of a panicle are 

 longer than the others, it is termed 

 a thyrsus. 



PANNI'CULUS CAENO'SUS. (from pan- 

 nioulm, a cloth, and carnosus, 

 fleshy, Lat.) A peculiar set of sub- 

 cutaneous muscular bands which 

 serve to erect the bristles, or 

 armour of certain animals ; as in 

 the hedge-hog, porcupine, &c. 



PANOPJE'A. A genus of bivalve shells 

 of the family Solenacea. The 

 Panopaea is a transverse inequilat- 

 eral bivalve, gaping at both extre- 

 mities. The hinge similar in both 

 valves, with an acute cardinal 

 tooth in each, and, on the right 

 valve, a little pit, which receives 

 the tooth of the opposite valve. 

 It is found both recent and fossil. 



PA'PEE COAL. A bituminous shale, 

 to which the name has been given 

 from its divisibility into extremely 

 thin leaves. 



PA'PEE NAU'TILTJS. Called also the 

 Paper Sailor. See Argonauta. 



PAP^LIO. (papilio, Lat. a butterfly.) 

 A genus of the family Diurna. 

 belonging to the order Lepidoptera, 

 The butterfly. The species are 

 numerous. It has been well ob- 

 served that the chrysalis is the 

 tomb of the caterpillar, and the 

 cradle of the butterfly. 



PAPILIOKA'CEOUS. Kesembling a but- 

 terfly. In botany, the corolla is 

 called papilionaceous when it con- 

 sists of five petals of particular 

 forms, of which the uppermost is 

 generally the largest, and turned 

 back ; the two next resemble each 

 other, and are called the alae ; the 

 two lowermost are generally united 

 by their lower edge, and form a 

 keel-like figure, and are, from that 

 circumstance, called the carina or 

 keel; the two last, so united, 

 contain, and protect, the internal 

 organs. 



PAPI'LLA. (papilla, Lat.) This word 

 is generally used in the plural, 

 papillae. Malphigi first discovered 



this structure in the foot of the 

 pig, and gave to it its name. The 

 external surface of the skin presents 

 a great number of minute pro- 

 jecting filaments; these are the 

 papillae. " It is probable," says 

 Dr. Eoget, " that each of these 

 papillae contains a separate branch 

 of the nerves of touch, so that we 

 we may consider these papillae as 

 the principal and immediate organs 

 of touch. The papillae are much 

 more easily perceived on some 

 parts than others, but no where 

 are they more perceptible than on 

 the tongue, where, more especially 

 in a morbid condition of the body, 

 they are frequently much elevated." 



PAPI'LLOSE. In botany, a term applied 

 to stems covered with soft tubercles; 

 also to leaves covered with fleshy 

 dots or points. 



PA'PPUS. (pappus, Lat. thistle-down, 

 TraTrTra?, GT.) The feathery appen- 

 dage that crowns many seeds which 

 have no pericarpium ; a particular 

 form of calyx, of which we have a 

 familiar example in the dandelion. 



PAEA'BOIA. (parabola, Lat.) One of 

 the five conic sections : thus, if a 

 cone be cut by a plane parallel to 

 one of its sloping sides, the section 

 will be a parabola. 



PAEADO'XIDES. The name given by 

 Erongniart to a genus of trilobites. 

 The Olenus of Dalman. "This 

 genus," says Sir E. Murchison, 

 " may always be recognised by the 

 ends of all the lateral ribs termi- 

 nating in deflected points, some of 

 which extend in spikes beyond the 

 tail." In Pictet's system, Parad- 

 oxides constitutes a family com- 

 prising the genera Remopleurides, 

 Paradoxides, Hydrocephalus, Jao, 

 Arionellus, Ellipsocephalus, Olenus, 

 Conocephalites, Peltura, and Tri- 

 arthrus. 



PARALLE'LOGEAM. (from Tra/mXXi/Xo? 

 and ^pdfifjLa, Gr. paralUlograme, Fr. 

 par allelogr ammo, It.) In geometry, 

 a right-lined quadrilateral figure, 



