554 IANTHINID.E. 



viewed dorsally, appears to occupy only one-fifth or one- 

 sixth of the entire length : its apex is flattened, or even 

 sunken. The body- whorl is not angularly contracted at its 

 circumference, but is ventricose and rounded ; yet the arch 

 of its lateral outline is not regular, but displays a little 

 flatness both above and below the middle of it : the base 

 is not at all compressed, but distinctly rounded. The 

 aperture, which is extremely ample, and patulous, occupies, 

 for the most part, four-fifths of the length of the shell ; it 

 is of a somewhat abbreviated ovate shape, but its regularity 

 is affected by the roundness of the last whorl, and the 

 comparative straightness of the pillar lip, the angle of 

 whose union is always a very obtuse one. The general 

 arcuation of the outer lip, which recedes but little at the 

 base, is almost uninterruptedly semicircular ; it rises, 

 instead of declining, at its junction with the body, and 

 unites with the pillar in a curved line, thus rendering the 

 anterior extremity of the mouth rounded instead of angular. 

 It is not angularly incised in the middle, but only sub- 

 angulately sinuated ; this character is observable through 

 the lines of growth, even where the lip (too commonly the 

 case with all Ianthhur) has been broken. The pillar lip, 

 which is rather broad, and convexly reflected, is not oblique, 

 but is often a little sinuous ; it does not quickly attenuate, 

 but continues of nearly the same width down to its anterior 

 extremity. Behind it lies a narrow subumbilical cavity, 

 that is partially concealed by the curl of the upper portion 

 of the pillar-lip. Foreign individuals often measure an 

 inch in both directions, but the few individuals thrown 

 upon our own coast are not quite so large. 



In our description we have been careful to particularize 

 the points in which the species differs from the globosa of 

 Swainson, its nearest congener ; the narrow pillar-lip, and 



