254 TYRAMIDELLIDiE. 



longitudinal riblets, that interrupt, as it were, the course of 

 the less elevated lines that wind around the volutions. The 

 former series, which reach from suture to suture, but cease 

 upon the slope or lower half of the body whorl, where the 

 spiral lines, though finer and less prominent, are alone 

 present, are very numerous on the principal coils (from 

 twenty to thirty on the penult turn), and become more 

 dense and approximate towards the outer lip. The latter, 

 likewise, are equally distributed over the surface of each 

 whorl, and are closely disposed and rather numerous, being 

 at least seven in number, but often appearing more, some 

 of them being double. The spire, which continuously 

 tapers to a very fine point (the nucleus is exserted and 

 much distorted), consists of eight or nine shortish whorls, 

 that are profoundly divided by a moderately oblique 

 suture ; they are of gradual longitudinal increase, range in 

 convexity from slightly to moderately rounded, incline a 

 little inwards at their bases, and are not scalar, though 

 oftentimes rather abruptly prominent above. In adult 

 examples the basal declination of the body, which therein 

 composes one-fourth to one-fifth of the entire length, is 

 rounded but rather sudden. The mouth (whose matured 

 peristome is complete) does not usually fill one-fourth of the 

 total length, and has a narrow ovate figure, the symmetry 

 of which is disturbed by the obtuse angle formed by the 

 columella with the base of the preceding turn, and the 

 abrupt angular contraction of its upper or posterior corner ; 

 it is well-rounded and not at all effuse below. Of the two 

 lips, the outer one is simple, acute, and moderately arcuated; 

 three-fifths of the inner one is occupied by the straight 

 pillar-lip, which, although not appressed, is reflected and 

 moderately broad. A line and a third is the average basal 

 diameter of individuals that measure four lines in length. 



