102 ASSIMINEID.E. 



apparently margined underneath by a darkish line, which re- 

 presents the periphery of the preceding whorl seen through 

 the semitransparent outer shell : mouth shaped as in the last 

 species, but not so small in comparison ; its length equals that 

 of one-half of the shell : outer lip incurved at the upper corner 

 and expanded below : inner lip very broad, and reflected over 

 the pillar, which is thickened and has a small umbilicus be- 

 hind it : operculum rather thin, slightly and closely striated ; 

 spire very small and sunken, with two obscure whorls. L. 0-075. 

 B. 0-0625. 



HABITAT : Under stones and clods of earth among 

 mud, and in caves and rocks 



" Upon the beached verge of the salt-flood," 



inside the Chesil Bank at Weymouth, and in the island 

 of Sark; Whitecliff Bay, Isle of Wight (Forbes); Ex- 

 mouth (Clark) ; Lands End (Hockin). It lives with 

 Truncatella truncatula, Melampus bidentatus, M. myoso- 

 tis, var. ring ens, and Otina otis. A. littorina is widely 

 distributed throughout the Mediterranean and Adriatic; 

 the Baron de Paiva and Rev. R. B. Watson have found 

 it at Madeira, and Mr. M f Andrew at Teneriffe. Southern 

 specimens are more deeply coloured than ours, but similar 

 in all other respects. 



Philippi placed this species in the genus Truncatella ; 

 and in the plate illustrative of his paper (Arch. f. Naturg. 

 1841, t. v. f. 7) it is represented as having the eyes 

 placed on the inner base of the tentacles. This mistake 

 as to the position of the eyes was, to a certain extent, 

 pointed out by L. Pfeiffer, who proposed a new genus 

 (Paludinelld) for the reception of the present species. 

 The Baron de Ryckholt (Journ. de Conch, viii. 187) 

 assigned it to the genus Menestho of Miiller ; but he 

 gave no reason for such a strange allocation. 



In Thorpe's ' British Marine Conchology' it bears 

 Mr. Metcalfe's MS. name of Cmgulal globularis. 



