240 ME. A. S. KEXXAED & ME. B. B. WOODWARD OX [vol. lxxv, 



Succixea pfeiffeei Rossmassler. 



Common at Barnwell Abbey and abundant at Barrington, where 

 the variety scliumaclieri Andrese was common. 



Succixea obloxga Draparnaucl. 



Very common at Barrington and common at Barnwell Station. 

 All the examples are. however, typical. There is a marked absence 

 of the var. agonostoma Kust. found at Ilford (Essex), Stutton 

 (Suffolk), and Woodston (Northamptonshire). 



Limxjea palusteis (Miiller). 



The examples from Barrington are dwarfed. The specimens 

 from Barnwell Station may be referred to the var. diluviana 

 Andrea?. 



LlMX^A TETTXCATULA (Miiller). 



All the examples of this species are small. Recent examples are 

 often much larger. 



BlTHTXTA TEXrACULATA (Liline). 



The specimens from Barnwell Abbey are, as a rule, large, with 

 an inflated body-whorl, and approximate to recent examples. 



Uxio littoealis Lamarck. 



Common at Barnwell Abbey. The shells are, however, smaller 

 than those from Crayford and Clacton, but larger than Swanscomb 

 specimens. 



COEBICTILA ELUMIXALIS (Miiller). 



Common at Barnwell Abbey and Grantchester ; rare at Bar- 

 rington, where it only occurs in the lowest bed. The examples are 

 small, but this is probably due to their environment, for English 

 Pleistocene shells from gravels are always small. The largest 

 examples occur in the brickearths of Crayford and Stutton, and 

 these are much larger than any Continental Pleistocene specimens 

 that we have seen. 



Conclusions. 



' Strata are known by their contained fossils ' is a statement as 

 true of gravels as it is of limestones. In the neighbourhood of 

 Cambridge are a series of gravels which, on stratigraphical evidence, 

 have been considered to be of one age ; yet an examination of the 

 mollusca shows clearly that several horizons are represented, cover- 

 ing a vast period of time. 



The oldest is the basement-bed at Barrington, yielding mam- 

 malian remains which may well be correlated with the older brick- 

 earths of Grays. The next stage is represented hj Barnwell 

 Abbey, East Road, Barnwell, Milkman's Lane, Grantchester, and the 

 lower bed of the Downing Section. They are the equivalents of 

 the Upnall (Ilford) deposits in the Thames Valley. Trumpington 

 may belong to this stage, or, more probably, may be slightly newer. 



