The land and freshwater shells of the British Isles : with illustrations of all the species . uctor muscle, which is placed in, or near, thecentre of the body. In the latter and much largergroup there are two distinct adductor muscles on theright and left sides of the body. In addition to the impressions made in the interiorof the valves by these muscles, there is a groove calledthe pallial scar, which is caused by the muscularattachment of the mantle to the shell; it is not shownin the woodcut, but if a specimen of Unio tumidus beexamined, it will be seen that it extends from one INTRODUCTION
The land and freshwater shells of the British Isles : with illustrations of all the species . uctor muscle, which is placed in, or near, thecentre of the body. In the latter and much largergroup there are two distinct adductor muscles on theright and left sides of the body. In addition to the impressions made in the interiorof the valves by these muscles, there is a groove calledthe pallial scar, which is caused by the muscularattachment of the mantle to the shell; it is not shownin the woodcut, but if a specimen of Unio tumidus beexamined, it will be seen that it extends from one INTRODUCTION. adductor scar to the other, following, at a shortdistance from the edge, the curve of the lower margin. The exact position of the mnbones is more clearlyindicated in the second figure than it is in the first, bythe small white patch seen on the apex of each figure also shows the hinge and teeth, which inthe Unioiiidce are lateral only; they are described inthe body of the work (see pp. 11-12). Cardinal teeth are those placed close to the um-bones (see Sphcerium corneum, p. 3).. PERIPHERY • UMBILICUS OPEROUUJM The above three figures show the several parts of aunivalve shell. xxviii INTRODUCTION. Collecting.—The requisites for collecting our land andfresh-water shells are as simple in construction as theyare few in number. A net of coarse canvas, or betterstill, a scoop made of copper-wire gauze, and havinga zinc rim fitted with a socket by which it can beattached to a pole or a walking-stick; a plentifulsupply of pill-boxes of various sizes ; a wide-mouthedbottle or two, with tightly fitting corks ; and a pocketlens for examining minute species, will complete thecollectors kit. Aquatic species may be taken bysweeping with the net or scoop among the water-plants which float on the surface or grow on the sidesof ponds, rivers, and ditches. Those which burythemselves in the mud can be obtained by scrapingalong the bottom with the scoop, which should thenbe moved to
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Keywords: ., bookcentury1800, bookdecade1880, bookidlandf, booksubjectmollusks
