A conchological manual . ingto the proportion which it may bear to the rest of the the canal of Ranella ranina (fig. 393 in the plates), maybe described as short; while that of Murex haustellum,(fig. 396, pi.) is long. When it is wide near the aperture, andbecomes gradually contracted towards its termination, it is saidto be tapering, as in Pyrula (fig. 388, pi.) ; when the termi-nation is sudden, it is described as truncated. If, on placingthe shell upon a plane, with the aperture downwards, the canalis seen to rise upwards, it is recurved. In Buccinum andNassa it is turned suddenl
A conchological manual . ingto the proportion which it may bear to the rest of the the canal of Ranella ranina (fig. 393 in the plates), maybe described as short; while that of Murex haustellum,(fig. 396, pi.) is long. When it is wide near the aperture, andbecomes gradually contracted towards its termination, it is saidto be tapering, as in Pyrula (fig. 388, pi.) ; when the termi-nation is sudden, it is described as truncated. If, on placingthe shell upon a plane, with the aperture downwards, the canalis seen to rise upwards, it is recurved. In Buccinum andNassa it is turned suddenly over the back, and forms a short,curved elevation; it is then described as recurved and vari-cose. If the edges meet, so as to form a tube, it is said to beclosed, as in some species of Murex and Typhis. The pos-terior canal is, in some cases, free, or standing out from thespire, as in some species of Ranellae; while in others it isdecumbent, running up the sides of the spire, as in Rostellaria (fig. 402, pi.). Fig. 51, Fasciolaria, truncated; 52, Nassa, recurved, varicose53, Cerithium, recurved; 54, Typhis, closed. INTRODUCTION. 27 Lips, or edges of the Aperture. The part of the edge of the aperture next to the body whorlis named the inner, or columellar lip. Posteriorly it com-mences at the point of union with the outer lip, where thattouches the body whorl, the junction being generally markedby an angle, and sometimes by a canal. Anteriorly itterminates where there is generally seen a notch or canal,or sudden angle, from which the outer lip proceeds. The partwhich setting out from the body whorl, and proceeds outwardsat a distance from the axis, till it reaches the anterior canal ornotch (or its place in case of absence) is named the outer many cases the edges are united in such a manner, that itis difficult to distinguish where the inner lip terminates, andthe outer lip commences: when this is the case, it is usual todescribe the margin or peritreme, as a
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Keywords: ., bookcentury1800, bookdecade1840, bookidconchol, booksubjectshells
