CONCHOLOGY. 



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and equally narrow mouth lengthways, which runs into a 

 ftiort gutter at the top. Molt authors have added ano- 

 ther charafter, that is, of always being thorny or I'piked, 

 bumped, orotherwife rough all over the I'urface, like the 

 ipikes or aCperities of rugged rocks, from which it oh- 

 tained the Latin name of miirex, the Englifh one oi rocks, 

 and the French n:\me of rochers; but this charaii^er does 

 not hold throughout the genus. 



The nnirices are divided into four genera, viz. i. Mu-- 

 rex, or rock-fliells, whofe mouth is oblong, narrow, and 

 ends in a gutter at the top ; the clavicle or turban being 

 generally fhort or nearly flat, and the pillar wrinkled or 

 plaited. They are molt commonly very thick (liells, and 

 extremely rugged on the outfid-, from being wrought 

 fcith humps, prongs, foliations, and other fimilar works. 

 This genus is very numerous, and Ibme of the fpecies 

 are vaftly large and heavy. 



2. Rhombi, or (hells wJiofe fubordinatc charaffer is to 

 have always a rhombic fliape or contour, from which par- 

 ticular alone, as it carries an idea of the fubjeiSs pro- 

 pofed, they have the name of rhombi. In the elder au- 

 thors we find (liells called rhombi, but which appears to 

 be a mere name without meaning or application. Thus 

 Columna makes rhombus, tuibo, ftrombus, and trochus, 

 all fynonymous. ..Liller calls the volutes and olives, 

 rhombi, or llrombi ; and Sibbald, Woodward, &c. do the 

 fame; but in the modern authors, we feldom fee the 

 name of rhombus ufed. This confufion apparently arifcs 

 fror.) the double meaning of the Latin word rhombus, 

 vhich not only Ognifies a lozenge or rhombic figure, but 

 alfoa reel, a fpinning-whecl, a whirl, or other rolling in- 

 ftrument; and it is from tiiis lalt funilitude the olives 

 and fuch like fliells have been called rhombi, by the elder 

 authors, and not from a lozenge or rhombic figure, as 

 ibme have erroneoufiy imagined. This genus is not fo 

 numerous as the preceding, but contains many beautiful 

 Ihelis ; and ionie very large and heavy. There is an ele- 

 gant fodil fpecies of rhombus, not yet difcovered in a 

 living Rate, found in France, and in Hordell clitfs near 

 Chiirtchurch, in Hampfliire. It is curioufly figured in 

 Brander's Folfilia Hantonienlia. 



The third genus is the alatse, or winged rocks; fo named 

 by moll authors from their lip being greatly extended, or 

 expanded outwards, like a fl.ip or wing. Some few kinds 

 have the wing quite fimple, or with the edges even ; but 

 the greater part of thefe, as alfo of the pporrhais, have 

 aUb near the top of the mouth a broad hollowed finus, 

 called the/rrc/, from which appendage Lifter names them 

 purpura feu buccbia bit:nguij. Rumphius and Meufchen 

 make a diftinc't genus of them, which they call alatje. 

 Davila ranks tiiefe by themfelves in the third genus of 

 his murices, by the name of fimple v/inged Ihells; and 

 Linnaeus ranks all the winged (liells together in bis genus 

 Urombus. This genus is very numerous, and contains 

 many beautiful and coftly (hells. - An elegant and large 

 folfd kind of this (hell, not yet difcovered living, is alfo 

 found in Hordell clifts in H.impfliire, and figured in Bran- 

 der's FolTilia Hantouienfia. 



The fourth genus of murices is the aporrhais, or fpider- 

 fhells, whofe edges are fet with ftrong and large prongs 

 or fingers ; hence they are called fpider-lhells, aevil's- 

 cla.vs, Sec. Davila makes thele his fourth genus of mu- 

 rices, which he calls winged murices with prongs or fin- 

 gers ; but all the other authors have intermixed them 

 with the alatse. The (pecies are few, but they are elegant 

 Ihells. — See fpecimens of them in the annexed copper- 

 plates. A fpecies of raurex has been found on the coafts 

 of Guayaquil and Guatimala in South America, which is 

 faid to produce a purple colour fuperior to the famed Ty- 

 rian dye. Tae abb^Raynal fays of it, that no colour yet 

 knov;n can be compared with this, either as to lultre, live- 

 Jinefs, or duration. The progrefs cl modern cliemiltry, 

 however, in the art of dying, has fuperceded all thele 

 far-fetched encomiums. Thefe terminate all the families 

 and gcr,cra of univalve fnells. They are certainly the 

 Vol. V. No. 151. 



moft numerous of the tedaceous animals, and greatly ex- 

 ceed the two general divifions of bivalves and niultivalves 

 joined together. In tliis afi'emblage of univalves the (tu- 

 pendous works of the creation are fingularly manltelted, 

 by the immenfity of beauties in their colours and ftruc- 

 tuies. On this account it is that univalves are in general 

 the choiceft objeits of colleftors, and bear more value 

 than bivalves or niultivalves. 



O/BirAirES, or DOUBLE SHELLS. 



Thefe are compofed of two pieces, or parts, which, by 

 means of a connexion by hinges, play on each other, fo as 

 to open or (hut, and perform all other f unftions nt cefl'ary to 

 the economy or way of life of the animal mcluded in them. 

 In relation to tlie filhes which inhabit them, they are de- 

 fcribed under their generic names, fioni the lylfeniof 

 Linnaeus ; it being the bufinefs of conchology to defcrtbe 

 the (hells, and not the animals, or any of their parts. 



This divifion of bivalves may be arranged under three 

 general heads, viz. (hells that have unequal valves, and 

 (hut clofe ; as the efcallops, oyfters, dnomise, &c. fhells 

 that have egual valves and (hut clofe; as the cockles, tel- 

 Icns, rnufclcs, &c. and (hells with valves that ne'ver Jhut 

 clofe, but are arlways open or gaping in fome part; as the 

 tridacna;, bafon-lhells, or bears paws, thechamw, pinna-, 

 (blenes, &c. Under thele thiee arrangements all the bi- 

 valves yet known may be ranked. Thefe three arrange- 

 ments are alio, general ones; but the chief or effential 

 charafler of bivalves is their cardo, or hinge ; and there- 

 fore by that charaifter alone the families are diftir.guilhed. 



Lifter begins his hiftory of Ihells with the bivalves, 

 which he divides into two parts, and into twelve (ami- 

 lies. In his arrangement he has great regard to the cha- 

 r.after of the hinge, though he does not entirely build 

 upon it. His method, however, wants correflion in his 

 third family, or margaritifera; ; in his fevenih family, his 

 placing the Noah's arks or boats, as mulcles; in his ninth 

 family of tellens, which is not truly defined; and, laUly, 

 in his making two families of the chama and chama plio- 

 las, which in reality have no pofitive character to diltin- 

 guifli them. Dr. Grew, in his Mufeum Regalis Societatis, 

 gives, as his feventh Icheme of (hells, that of the bivalves 

 and multivalves ; but it is (b confided as to be_ ufelefs as 

 a fyftematic work ; however, his two chief divifions ot 

 bivalves are into inarticulate, and articulate, hinges. 

 Breynius's Icheme of bivalves is very jejune and ufelels. 

 Argenviile divides all his bivalves into fix families, viz. 

 oylters; chamje ; mufcles, tellens, and pinnae"', coidi- 

 formes, or cockles; efcallops; and lolens. This author s 

 method is entirely arbitrary; nor does he charaAerize a 

 fingle family by the cardo or hinge. 



Gualtieii forms his- method from thofe whofe valves 

 and fides are equal or fimilar, which is his firft clals ; his 

 fecond clafs coiifills of thofe whole valves are equal, and 

 their fides unequal or diflimilar; and his third clafs is ol 

 (hells with unequal valves. By this ariangeinent he re- 

 jefts the hinges as characters, and mixes all the families 

 together, folely on account of their fimilar or di(iiniil.*r 

 fides; lb that it is impo(rible to collate his method in 

 fuch a manner as to be of much utility to the learner of 

 conchology. The method of Mr. Tournefort divides all 

 bivalves into two parts : firit, fuch as fliut dole all round ; 

 and, fecond, fuch as are alwa) s open or gaping in (onie 

 part. This divifion, though good, is incomplete, and his 

 families and genera are very arbitrary. Linnseus, in de- 

 fcribing the included animals or filh, divides all bivalves 

 into fourteen genera, which he charailerifes by tiieir 

 hinges in a very accurate manner; and his method feeir.s 

 to be the moft perfeft of any yet publithed. His arrange- 

 ment is as foilows: Mya, the pearl-oytter j folen, the 

 knife-handle; telllna, the tellen ; cardium, the cockle; 

 mattra, the pellucid oyller; donax, truncated or (int- 

 fided cockle; Venus, or concha-venerea, gaping ihtils, 

 fo named from their refemblance to the pudenda of wo- 

 men; fpondylus, the thorny oyfter j chaiiia, Ihells of the 

 t cockle 



