PEN 



[ 199] 



PER 



mains of an extinct genus. Subsequent 

 discoveries, however, prove that the pen- 

 tacrinus does still exist ; two species, the 

 Pentacrinus caput medusae, and the Pen- 

 tacrinus europseus, having been lately 

 discovered. Thus, probably, it may be 

 with many genera which, in ignorance, 

 geologists describe to be extinct, merely 

 because they have not met with living or 

 recent specimens. 



PENTA'CRINUS. This animal consists of 

 an angular flexible column, composed of 

 numerous joints, articulating by means 

 of cartilage, and perforated for the trans- 

 mission of a siphon, or intestinal canal, 

 and sending forth at intervals, in whoi'ls, 

 several articulated cylindrical branches, 

 curving into a hook at their summit ; 

 fixed at its base, and supporting at its 

 free extremity a cup-like body, contain- 

 ing the mouth and larger viscera, con- 

 sisting of several pieces, terminating 

 above in five or six dichotomizing, arti- 

 culated, semi-cylindrical arms, fringed 

 with a double series of tentacular jointed 

 digitations, furnished below on each side 

 with a series of minute suckers. These 

 arms, when expanded, resemble a star of 

 five (or six) rays ; and when they con- 

 verge, a pentapetalous or hexapetalous 

 flower. The whole animal, when alive, 

 is supposed to be invested with a gelati- 

 nous muscular integument. Rev. W. 

 Kirby, Bridg. Treatise. 



Two species of the genus pentacrinus 

 have been lately obtained ; one, the Pen- 

 tacrinus caput medusae, from the bottom 

 of deep" seas in the West Indies ; the 

 other, Pentacrinus europseus, has been 

 found on the coast of Ireland, attached 

 to different kinds of Sertularia and Flus- 

 tracea. The calcareous joints which 

 compose the fingers of the pentacrinus 

 europseus, are capable of expansion and 

 contraction in all directions ; now spread- 

 ing outwards, like the petals of an ex- 

 panded flower, and again rolled inwards 

 towards the mouth in the form of a closed 

 bud. These organs serve to seize, and 

 convey to the mouth, the food of the 

 animal. The number of bones in each 

 animal is computed at thirty thousand. 

 Dr. Buckland says that the number of 

 bones in the Briarean Pentacrinite, a 

 species beautifully described in his admi- 

 rable Bridgewater Treatise, exceeded a 

 hundred and fifty thousand. The num- 

 ber of bones in the fingers and tentacula 

 amount at least to a hundred thousand, 

 and fifty thousand more, which is consi- 

 derably under the real number, may be 

 added for the ossicula of the side arms. 

 Each bone requiring at least two fasciculi 

 of fibres, one for expansion, the other for 

 contraction, the Briarean Pentacrinus 



must have had three hundred thousand 

 fasciculi of fibres equivalent to muscles. 



PENTADA'CTYJ,. (from Trevre, five, and 

 daKTV\o, a finger, Gr.) Having five 

 fingers. Applied also to leaves. 



PE'NTAGON. (from Trevre, five, and ywvi'a, 

 an angle, Gr. pentagone, Fr. pentayono, 

 It.) A figure having five sides and five 

 angles. 



PENTA'GONAL. (pentagone, Fr. penta- 

 gonale, It.) Having five angles and five 

 sides; quinquangular. 



PENTAGONA'STER SE'MILUNATUS. A fos- 

 sil species of the Stella marina, found in 

 the chalk pits of Kent. 



PENTAGONA'STER REGULA'RIS. A fossil 

 asterite, or species of stella marina, found 

 in the chalk pits of Kent. 



PE'NTAGYN, from Trkvre, five, and yvvrj, a 

 woman, Gr.) A plant which has five 

 pistils. 



PENTAHE'DRAL. Having five equal sides. 



PENTAHE'DRON. (from TrkvTt, five, and 

 tdpa, a base, Gr.) A figure of five equal 

 sides. 



PENTA'NDER. (from Trkvrt, five, and 

 art]?, a man, Gr.) A plant having five 

 stamens. 



PENTA'NDRIAN. Five stamens ; having 

 five stamens. 



PENTAPHYLLOI'DAL. (from irdvre, five, 

 (pvXXovy a leaf, and tidoc, resemblance, 

 Gr.) Appearing to have five leaves ; 

 resembling five leaves. The Placentae 

 are all ornamented with a pentaphylloidal 

 flower. 



PENTELA'SMIS. (from irevTs, five, and 

 IXaoyia, a plate, or layer, Gr.) A spe- 

 cies of Anatifa, or of the Lepas of Lin- 

 nseus. 



PEPERI'NO. The name given by Italian 

 geologists to a particular form of volcanic 

 tuff, composed of basaltic scoriae . 



PERA'MELES. A genus of marsupialia. 

 The following description is from Major 

 Mitchell's Australia. " The most re- 

 markable incident of this day's journey 

 was the discovery of an animal, of which 

 I had seen only the head amongst the 

 fossil specimens of Wellington valley. 

 This animal was of the size of a wild 

 young rabbit, and of nearly the same 

 colour, having a broad head, terminating 

 in a long very slender snout, like the 

 narrow neck of a wide bottle ; and no 

 tail. The feet, and especially the fore 

 legs, were singularly formed ; the latter 

 resembling those of a hog, and the mar- 

 supial opening was downwards, and not 

 upwards, as in the kangaroo and others 

 of that class of animals. This animal 

 was discovered by our natives on the 

 ground, but when pursued it took refuge 

 in a hollow tree, from which they took it 

 alive ; all of them declaring that they had 



