250 



faintly and irregularly, but closely, striate, in the line of 

 growth : periphery rounded : epidermis thin : whorls 6-7, 

 convex, but a little compressed, the last equal to about 

 one-third of the shell, the two first whorls much smaller in 

 proportion to the rest : spire short, abruptly and bluntly 

 pointed : suture rather deep : mouth forming an oblique 

 segment of about two-thirds of a circle, furnished sometimes 

 with a small tubercular tooth on the columella, which is 

 placed nearly in the middle : inside slightly tinged with 

 reddish-brown : outer lip sharp, strengthened by a thick, 

 white, exterior rib, which is placed at a little distance from 

 the margin ; outer edge slightly reflected : inner lip spread 

 on the pillar : umbilicus small and shallow, contracted by a 

 slight ridge or crest at the base of the shell. L. 0-133. B. 0-6. 



Var. 1. bigranata. Shell rather smaller and thicker, and 

 having a tubercular tooth or denticle considerably within 

 the outer lip, as well as that on the columella. P. bigranata, 

 Rossmassler, Iconogr. ix, x. p. 27, f. 645. 



Yar. 2. albina, Menke. Shell white. 



HABITAT : Under stones, at the roots of grass, and 

 among dead leaves, everywhere from the Moray Firth 

 district to Guernsey, especially on the sea-coast. Var. 1. 

 Bath (Clark); Lulworth, Dorsetshire (J. G. J.); Ox- 

 fordshire (Whiteaves) ; Weston-super-Mare (Norman). 

 Var. 2. Somersetshire (Clark, Norman, and J. G. J.) ; 

 Oxfordshire (Whiteaves). I have also found a monstro- 

 sity in which the lower whorl is furrowed, and another 

 which has the periphery keeled, the former having been 

 apparently caused by a grain of sand adhering to the 

 mantle while the shell was in course of formation, and 

 the latter by an accidental fracture of the last whorl, which 

 obliged the animal to make a new mouth and to shorten 

 the base. As an upper tertiary fossil it is very common, 

 and often indicates the former presence of littoral con- 

 ditions, as this species not only peculiarly affects sandy 

 shores and maritime places, but is also washed down in 

 great numbers by estuarine rivers and thrown up on 



