A conchological manual . ritreme, as a whole, without distin-guishing the parts. The outer lip, sometimes called the rigidlip, or lahrum of continental writers, is sometimes acute, notbeing of thicker substance than the remainder of the other cases it is obtuse, or thickened and rounded at theedge. When thickened and turned backwards it is describedas reflected; when, on the other hand, it is turned inwardstowards the axis, as in the Cypraedae, it is inflected, or invo-lute. When it is toothed, a distinction must be observed asto whether the dentations are external or internal. If the
A conchological manual . ritreme, as a whole, without distin-guishing the parts. The outer lip, sometimes called the rigidlip, or lahrum of continental writers, is sometimes acute, notbeing of thicker substance than the remainder of the other cases it is obtuse, or thickened and rounded at theedge. When thickened and turned backwards it is describedas reflected; when, on the other hand, it is turned inwardstowards the axis, as in the Cypraedae, it is inflected, or invo-lute. When it is toothed, a distinction must be observed asto whether the dentations are external or internal. If theteeth are small and numerous, it is denticulated; if larger, itis dentated; when expanded into a kind of wing, as in somespecies of Strombus and Rostellaria, it is described as alated;and a family in Lamarcks system is named Alatse, fromthis very circumstance. In some of those which are expanded,the expansion is divided into separate, attenuated portions,they are then said to be digitated. •28 INTRODUCTION, Outer Fig. 25, Helix, reflected; 56, Cyprsea, involute, denticulated; 57, Seraalated; 58, Mnxex, digitated; 59, Rostellaria, dentated. The inner lip, sometimes named the columellar lip, or labium is subject to similar variations as to thickness,dentition, &c. That portion of it which lies upon the body-whorl is frequently distinguished from that which intervenesbetween it and the notch or canal. De Blainville, restrictingthe term lip bord gauche to the former portion, applies theterm columella to the latter; and in some instances thismay be the more convenient method of describing the part inquestion. The columellar lip is sometimes detached entirelyfrom the body of the shell, as in Murex haustellum ; in othersit is decumbent, or lying over the last whorl, although quitedistinct, and in some cases, thickened, callous, or tumid. At the lower or anterior part, sometimes called the columella,there are in many instances flattened, laminated folds; theseare particularly
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Keywords: ., bookcentury1800, bookdecade1840, bookidconchol, booksubjectshells
