142 LITTORINIDiE. 



more or less opaque, dull-surfaced, smooth, and of an uni- 

 form tint of dirty fulvous or pale yellowish olive colour. 

 The spire tapers rather quickly to a somewhat pointed 

 apex, and is composed of six whorls, which are so flat in 

 the more characteristic examples, that the lateral outlines 

 are almost rectilinear. The volutions are moderate both 

 as to length and celerity of longitudinal increase, and are 

 sometimes bordered by a paler line beneath the narrow 

 simple and not much slanting sutural line that divides 

 them from each other. The body occupies from about 

 two-fifths to nearly half the dorsal length ; its basal slope 

 is often subangulated at the commencement, and is not 

 rounded, but more or less flattened. The mouth, which is 

 smooth internally, and has a shortened ovate contour, is 

 little more than half the length of the spire above it ; its 

 posterior contraction is not particularly acute. The peri- 

 stome is white, and distinctly continuous. The outer lip, 

 which does not advance at the base, is simple, acute, and 

 not disposed to expand ; it is arched in front, and straight- 

 ish or merely convex posteriorly. The upper or posterior 

 portion of the inner lip is straightish, and much slanting. 

 The pillar-lip is rather broad, and owing to the projection 

 of the extreme base of the body is tolerably long ; although 

 flattened, it is not appressed, but is usually raised a little 

 at the edge. It is reflected, but is not succeeded by any 

 real umbilicus, although a subumbilical crevice is generally 

 present. The common dimensions are the ninth of an inch 

 for the breadth, and a quarter of an inch for the length ; 

 but individuals of certain localities much exceed these 

 proportions. 



The variety stagnalis (Brown, Illust. Conch. G. B. pi. 

 9, f. 9), which is usually termed suhumbiUcata by collectors, 

 but docs not agree with Montagu's description of that 



