212 PROCEEDINGS OF THE MALACOLOQICAL SOCIETY. 



Clausilia laminata (Mont.), 2 examples. 

 C. bidentata (Strom), 1 example. 

 C. rolphii, Leach, 2 examples. 

 Succinea elegans, Risso, 6 examples. 

 Carychium minimum, Miill., common. 

 Limncea pereger (Miill.), 3 examples. 

 L. palustris {^InW.), 1 example. 

 L. tmncatula (Miill.), common. 

 Planorhis leiicostoma, Millet, common. 

 P. crista (Linn ), 2 examples. 

 Physa fontinalis (Linn.), 2 examples. 

 Bithynia tentaculata (Linn.), common. 

 Valvata cristata, Miill., 1 example. 

 Aciaila lincata (Drap.), 6 examples. 

 Pomatias elegans (Miill.), 4 fragments. 



Two species previously recorded, Hygromia striolata (Pfr.) 

 (^ = IIelix rufescens, auctt., 7ion Peun.) and Bithynia leachii {^he^-^.), 

 are missing, and these records are very doubtful. All the larger 

 forms are represented either by immature examples or by fragments, 

 but the large size of the smaller species is noteworthy, showing 

 clearly that the environment was congenial to the Mollusca. The 

 comparative abundance of Vertigo parcedentata is interesting, since in 

 the three other British deposits in which it occurred it was decidedly 

 rare. No stratigraphical evidence is available to fix the age of the 

 deposit, so one must rely solely on the Mollusca. There is only one 

 extinct species, V. parcedentata. In these Islands it is only known 

 elsewhere from Elie, Fifeshire, and Ponders End and Angel Road, 

 Middlesex. The first-named is early Holocene, the two latter, really 

 one deposit, late Pleistocene. The whole facies of the Apethorpe 

 Mollusca is so different from that of the Lea Valley beds that it 

 cannot be correlated with them, whilst the great difference in the 

 latitude prevents any comparison with the Scotch deposit. We are, 

 however, inclined to think it is late Pleistocene, and belongs to some 

 part of that vast period of time which elapsed between the deposition 

 of the Crayford brickearths and the Glacial Period, which latter 

 marks the end of the Pleistocene. 



