556 IANTHINID^. 



generally occupying, when viewed dorsally, about one- 

 third of the length ; it terminates in an acute and very 

 small distorted apex. The body-whorl is subangulated in 

 the line of its junction with the outer lip, and is usually, 

 in the adult, distinguished at that circumference by a 

 shallow, groove-like, spiral indentation. Beneath this the 

 raised longitudinal wrinkles, which above it are narrower 

 than their interstices, and run with an oblique arcuation, 

 suddenly diverge with an opposite inclination, and become 

 still more crowded than before. There are no spiral 

 striula?. The basal area is not compressed, but occupies a 

 considerable portion of the length of the shell ; its con- 

 vexity is rather less than that of the upper surface. There 

 is a small umbilicus, that is often but little apparent from 

 the reflection of the pillar lip ; which latter is elongated, 

 nearly straight, and, generally, of a paler hue than the 

 portion behind it. The aperture is longer than wide, and 

 is of a somewhat broad semilunar form. The sinus of the 

 outer lip is angular and profound. The length of our 

 Irish specimens is half an inch, and the breadth four lines 

 at the least. 



The figure which appears to represent this animal in the 

 beautiful designs of Quoy and Gaimard, differs from the 

 communis in exhibiting a foot much larger in proportion, 

 slenderer tentacles, a shorter float, and more scattered egg- 

 vesicles. Dr. Coates describes the float of exicjua as being 

 straight, narrow, flattened, and composed of small vesicles, 

 bearing the egg-vesicles on the under surface, attached by 

 a little line of pearly fibres. 



This species is much rarer than communis, and, like it, 

 oceanic. Turton announced its occasional occurrence, along 

 with the larger one. in the small coves about the Land's 

 End. Mr. Jeffreys has it in the Turtonian cabinet from 



