166 LITTORIxNIDTE. 



the basal level, the upper disk merely convex, the lower 

 area much rouiuled, but not produced. It is rather thin, 

 semitransparent, pure Avhite, highly polished, and ])erfectly 

 smooth, excepting at the mouth of the umbilicus, which is 

 furnished with bluntly rounded spiral costellrc that are 

 divided from each other by well-marked sulci. There are 

 three subcylindraceous whorls that are much less convex 

 above, but neither flattened nor sunken at the suture. The 

 spire is scarcely raised ; the two first volutions, of which 

 the apical one is blunt and almost level, are short, and of 

 slow increase ; the body is ample ; its suture is rendered 

 very distinct by the somewhat abrupt rise of the succeed- 

 ing whorl. The umbilical opening is large, and its cavity 

 deep. The aperture is almost orbicular, about as high as 

 broad, and occupies two-thirds of the entire length, and 

 about one half the basal diameter of the shell. The peri- 

 stome is continuous, but is only attached to the body by a 

 narrow strip. Both lips are acute, and greatly arched ; 

 the outer one is not expanded, except, perhaps, at the 

 base ; the pillar-lip is elevated, a little reflected, and longi- 

 tudinally wrinkled on its internal surface. 



Two very minute specimens were forwarded to us along 

 with Marri. imsilla by Mr. Jeflreys, and a larger one, 

 which measured rather more than a line in breadth, and 

 about three-sevenths of a line in length, was transmitted to 

 ns, as deserving our attention, by Mr. Alder of Newcastle- 

 on-Tyne, after whom, in the event of their not proving to 

 be the foreign species, we have doubtfully referred them 

 to, we would suggest they should be named. They w^ere 

 dredged by ISIr. Barlee, but he had not preserved their 

 locality. 



