44 LITTORINID^. 



more rarely it is of an unit'orm brownish black. There 

 are only four volutions, of which the first two are obscurely 

 defined (the apex being- almost always eroded, biit appa- 

 rently blunt) and very short ; the penult, by comparison, 

 is remarkably big, but its breadth is full double its height ; 

 the body somewhat ample, but rather broader than it is 

 long. These two last whorls are simply tumid, and swell 

 out at once, without any depression of surface, from the 

 very distinct suture. The body is twice the length of 

 the spire ; the base is short, and its declination, though 

 sudden, is well rounded. The aperture, which is rather 

 capacious, the basal portion not being filled up by any 

 broad confluence of the lips, occupies rather more than 

 one half the length of the shell ; it is longitudinally sub- 

 orbicular, scarcely, if at all, contracted posteriorly, and 

 broadly rounded anteriorly : the throat is chestnut or 

 rufous brown. The outer lip, which is simple and acute, 

 is peculiarly arched, and fully as much so below as above : 

 its junction with the body is rectangular. The free edge 

 of the pillar-lip is straightish (compared to the outer lip), 

 its attached margin is arcuated : the pillar is simple, short, 

 and neither twisted nor produced anteriorly, but tapering. 

 The specimens we have described from, measure only the 

 eighth of an inch in either direction. 



This shell is abundant in many localities on both our 

 eastern and western coasts, and is probably a common 

 species. On the rocky shores of the Isle of Man we liave 

 gathered it abundantly in the crevices of the rocks beside 

 Corallina officinalis. Mr. Alder and Mr. Hancock re- 

 mark that on the Northumberland coast it is found "on 

 rocks near low-water mark, bare of sea-weed, but covered 

 with Balani and muscle. The habitat of this little species 

 is different from that of the preceding, being always near 



