ACROLOXUS LACUSTRIS. 27 



B. AQUATIC. 



GASTEROPODA. 

 Genus ACROLOXUS, Beck, 1838. 



Acroloxus lacustris (Linne). Plate I, fig. 18. 



1758. Patella lacustris, Liuin', Syst. Nat., ed. x, p. 783, no. 672. 



1837. Acroloxus lacustris. Beck, Ind. Moll., p. 124. 



1863. Ayicyhis lacustris, Forbes and Hanley, Brit. Moll., vol. iv, p. 188, pi. cxxii, fig. 5. 



1862. Ancylus lacustris, Jeffreys, Brit. Couch., vol. i, p. 122, pi. viii, fig. 2. 



1872. Ancylus lacustris, A. and K. Bell, Proc. Geo]. Assoc, vol. ii, p. 215. 



1890. Ancylus lacustris, C. Reid, Pliof. Dep. Brit., p. 228. 



1897-1901. Velletia lacustris, Kennard and B. B. Woodward, Essex Nat,, vol. x, pp. 93 et seq., 1897; 



Proc. Malac. Soc, vol. iii, p. 203, 1899; Proc. Geol. Assoc, vol. xvii (tab.), 1901. 

 1903. Acroloxus lacustris, B. B. Woodward, Jonru. Couch., vol. x, p. 355. 



S-pecific Characters. — Shell minute, thin and fragile, oblong, twisted to the left, 

 indistinctly ornamented with fine radiating striae ; beak sharp and ridge-like, 

 placed close to the margin, turning obliquely to the left ; mouth oblong ; outer 

 lip membranous, reflected. 



Dimensions. — L. 6 mm. B. 2*5 mm. 



DLstrUmtion. — Recent : widely diffused in England ; less plentiful and more 

 local in Wales, Ireland, and Scotland south of Al^erdeen ; abroad from Finland to 

 Sicily (J. W. Taylor) ; Madeira (Bourguignat) ; North Africa (Gr. 0. Sars). 



Fossil : Icenian Crag : Bramerton (A. Bell) ; Freshwater bed, 

 West Runton, Pleistocene of England : Barnwell, Glrantchester, Hitchin, Barry 

 Docks. English Holocene. 



Pleistocene : Menchecourt, lacustrine beds near Paris ; Burgtouna and Miil- 

 hausen in Thuringia. Holocene : Sweden and Denmark (Nordmann). 



Remarl's. — This species was reported from the Icenian Crag in 1872 by Messrs. 

 Alfred and Robert Bell, but has been rejected by Messrs. Kennard and B. B. 

 Woodward from their list of British non-marine Pliocene Mollusca on the ground 

 that the specimen cannot now be traced. It seems to me improbable that a 

 mistake could have been made by two such competent and careful observers. 

 Mr. A. Bell, who only survives, informs me he has no doubt as to the correctness 

 of the identification. To the best of his belief he found the specimen in question 

 at Bramerton. 



The figure now given is from a Recent shell. 



