KENNAED & WOODWARD: ON" HELICELLA CRAYFORDENSIS. 271 



intus yalde labiatum, labio remotiusculo, raarginibus subconvergen- 

 tibus, margine inferiori fere recto, columellari subrecte descendente, 

 supra umbilicum pervium subexpanso. Diam. max. 6 5, min. 6 mm. ; 

 alt. 3-8 mm. ; apert. 2-8 X 2-3 mm. 



Horizon and Localities. — Pleistocene at Crayford and Erith (Kent), 

 Ilford and Clacton (Essex), Brentford (Middlesex), Barnwell (Cam- 

 bridgeshire), and Woodston (Huntingdonshire). 



The characteristic feature of the species is the flattened basal 

 margin of the peristome that imparts a slightly quadrate appearance 

 to the aperture, whilst the internal rib at this point is in some 

 specimens so thickened as to suggest on casual inspection a tooth-like 

 protuberance. 



From H. caperata it differs in being smaller and more depressed, 

 with the umbilicus eccentric as in H. gigaxi ] whilst the striae are 

 less regular than in H. caperata and not so pronounced, the whorls 

 are more convex, and the periphery not so keeled. 



From H. candidula it is similarly distinguished, save in the matter 

 of size. The whorls, moreover, in H. candidula increase more rapidly 

 in size than they do in the new species. 



From the small form of S. gigaxi, H. crayfordensis is at once 

 separated by the irregular character of its striation. 



Some of the specimens from Ilford and Woodston, judging by the 

 dimensions cited by Mr. Jackson (loc. cit.), are slightly larger than 

 those we have seen. 



