POLYGON UM. 



I'OLYODONTA. 



|M 



It dye* wool of yellow colour. The seeds, according to BullUrd, 

 we used in Mm* of the French province* instead of pepper. The 

 leaves are to acrid a* to act ai vesicants. It U a native of England in 

 ditches and wet place*. 



P. one-Ware ha* from one to three flowers together, axillary lanceo- 

 lete leave*, or elliptical plane stalked lanceolate acute ocrete, with few 

 dutant simple nerve* at length by growth becoming torn, a triquetrous 

 nut with raised points shorter than the perianth. Its numerous seeds 

 supply abundant food for small birds ; they are said to be emetic 

 and cathartic. Thunberg says that in Japan a blue dye is prepared 

 from this plant. 



There are many other species of Polygonum, natives of Great 

 Britain and other part* of the world, but too numerous for descrip- 

 tion here. /'. tinctorium is cultivated in France and Flanders on 

 account of the fine blue dye extracted from it The seeds of P. 

 barbalum are used in medicine by the Hindoo practitioners, and are 

 said to ease the pain of griping in the colic. The leaves of /'. hitpidum 

 are said by Hnmboldt to be substituted in South America for tobacco ; 

 and P. (oli-kamorrMdale is esteemed in Brazil on account of its 

 astrincency in baths, poultices, 4c. The juice, as well as an infusion of 

 the ashes when burned, is employed by the Brazilians in the clarifica- 

 tion of syrup and the condensation of sugar. 



P. Payopyrum, the Buck-Wheat, U now referred to Pagopynm 

 rtfulentum. [FAGOFTBCM.] 



(Lindley, Vegetable Kingdom ; Babington, Manual of Britith Botany ; 

 Burnett, Outluia of Botany ; Lindley, Flora Medico,) 



POLY'GONUM (Schumacher), a genus of Molltuca. 



POLYOY'UA, a genus of lldidda. 



POLYHAL1TE. [MAOSEMJL] 



POLYHYDRITE. [!BOK.] 



POLY'LEPAa [ClRRII'EDIA.] 



POLYLITE, a form of Augite. [AuoiTB.1 



POLYMIGNITE, a Mineral, consisting of Titaniate of Iron, Zircon, 

 &c. It occurs crystallised. Primary form a right rhombic prism. 

 Fracture conchoidaL Hardness, scratches phosphate of lime, and is 

 scratched by felspar. Colour black. Lustre nearly metallic. Opaque. 

 Specific gravity 4-806. Before the blow-pipe infusible ; acted upon 

 by sulphuric acid, when reduced to fine powder. It is found in 

 imbedded crystals at Frederiksvarn in Norway. The following is the 

 analysis by Berzelius : 



Titanic Acid 49'3 



Oxide of Iron 12-2 



Oxide of Cerium 6-0 



Oxide of Manganese 27 



Zirconia 14-4 



Yttria 11-5 



Lime 4-2 



Magnesia, Potash, Silica, and Oxide of Tiu . traces 



99-3 



POLYNE'MUS, a genus of Fishes, placed by Cuvier in his third 

 division of the Percida, the species of which are distinguished by the 

 ventral fins being inserted farther back than the pectorals. These 

 fishes are further distinguished by having several long filaments 

 beneath the pectoral fin ; these are, in fact, free rays of- that fin : their 

 teeth are minute and dense as the pile on velvet, or recurved like the 

 teeth in a carding-machine ; they are found on both jaws, as well as 

 on the vomer and palate. The general form of the body of the Poly- 

 nemi somewhat resembles that of the perch ; the muzzle projects over 

 the mouth ; the eyes are rather large and placed very forward ; the 

 dorsal fins are short and widely separated, and the caudad fin is large, 

 and more or less forked. The scales extend on the fins, as in many of 

 the Scimida, which these fishes appear to approach in some other 

 characters. 



Considerable interest is attached to the Polynemi on account of 

 their yielding isinglass. This fact was first made known by Dr. Cantor, 

 who found that several species of Polynemui might be used for 

 obtaining isinglass. 



" The species best known," lays Dr. Cantor, in a communication to 

 the Zoological Society, " is the Polynemui Ritua of Hamilton (P. longi- 

 flit, Cuvier; the Tupsee, or Mango Fish, of the Anglo-Indians) : this 

 inhabit* the Bay of Bengal and the .-estuaries of the Ganges, but enters 

 the mouths of the rivers even higher up than Calcutta during the 

 breeding season (April and May), when the fish is considered in its 

 highest perfection, and is generally sought as a great delicacy. This 

 specie* is the smallest, for it* length seldom exceeds eight or nine 

 inches, and one inch and a half or two inches in depth." It is remark- 

 able for the great length of filament*, or free rays, of the pectoral fins, 

 thene being about twice the length of the body, and seven in number 

 on each side. P. aurau and P. Toptui of Hamilton, Dr. Cantor states, 

 are closely allied to this species. " Polynemtu Sett, Hamilton (P. plebeiui, 

 Broussonnais; P.lineatut, Laodpcde), is the Suleah Fish first mentioned 

 in Parbury'a ' Oriental Herald,' as yielding isinglass. This species, as 

 well as another clowly allied to P. quadrifUii, Cuvier, which I have 

 dissected, figured, and described, under the name of P. Salliah (Sac- 

 colih), appears to be equally plentiful, in shoals, all the year round, in 

 the mtuaries of the Ganges, and is appreciated by Europeans for its 

 excellent flavour : both specie* attain a size from three to four feet in 

 length, and eight to ten inches in depth." ( - antor.) 



Besides these species found on the coast of the mainland, two other 

 species of Polynemia, P. hejccuiemui and P. heptadacttiliu, have been 

 discovered off the coast of Java. On the coast of Africa and in the 

 West Indies, certain species of the present genus are found. One of 

 the African special is confounded by Cuvier with the Indian P. longi- 

 Jilu, and the mistake has been rectified by Mr. Bennett It appears 

 that this species (which is in all probability the Pent amenta of Artedi, 

 on which LinnoMia established his P. i/uint/uaritu) differs from the 

 Mango Fish of India in the number of free rays to the pectoral fins, the 

 latter having seven rays, and the African species only five. Messrs. 

 Cuvier and Valenciennes, not having found any species of Polynemui 

 with so few aa five free rays, and those longer than the body, imagined 

 that the P. quim/uariia was founded on a multilated specimen. Several 

 individuals however having this character being discovered by Captain 

 Belcher, K.N., during his survey of a part of the Atlantic coast of 

 North Africa, Mr. Bennett proposed to name the species after Artedi. 



ta Aiietiii. 



The second African species belongs to that section in which the 

 free rays of the pectoral fins are short, and has received the name of 

 Polynemui qiuulriflw. 



rolynrmut 



/r 



(Cuv. ct Vat.) 



In the American Polynemui (P. Aiiurieanue) there are seven free 

 rays to the pectoral fin, and these scarcely reach the tip of the ventral 

 fins : it is about one foot in length, of a silvery colour ; the pectoral 

 fins are almost black, and the other fins are spotted with black. 



POLYODONTA (' many-toothed' tribe), a name applied by Lamarck 

 and M. De Blainville to the Arcacea [ABCAD.*:] of the former, the 

 Ark-Shells, 4c., of collector", comprehends the forms collected by 

 Linnieus, in his 'Systema Nature;,' under the genus Area, and those 

 designated by more modern zoologists as the genera Area, Cucullaa, 

 Pectunculut, and tfucula. 



Lamarck's Arcacea constitute a part of his Conchiferes Ti<nuip6des, 

 and are arranged by him between the Cardiaccee and the Trigonees. 



De Blainville places his family Polyodonta or Arcacds between the 

 Mylilacea, and Submytilacea. 



Lamarck thus defines the family : 



" Cardinal teeth small, numerous, entering, and disposed in each 

 valve in either a straight, a curved, or a broken line." 



M. Hang makes the Arcadrt consist of tho genera Cucullaa, Area, 

 Pectuncului, Nueula, and Trigonia, and gives the following as the 

 character of the family : Animal having the mantle entirely open 

 throughout its circumference, excepting towards the back, without 

 tubes or any particular aperture!*, and partially adherent ; sometimes 

 prolonged backwards; the foot always very considerable. Shell 



