84: JOURNAT, OF CONCHOLOGY, VOL. I4, NO. 3, JULY, I913. 



not hitherto been recorded in Britain, and Helicella candidula Stiider, 

 though noticed as a Pleistocene aberration from the modern form of 

 Helicella caperata Montagu, has not been up to the present referred 

 to this continental species. Again two of our present day species 

 which occur in great numbers throughout the deposit, Hygromia 

 hispida and Cochlicopa lubrica, show a very marked difference in size, 

 enabling one to reaHze the fact of the decadence in later times of 

 certain weaker species, once perhaps dominants, before the advance of 

 the modern dominant types. 



The deposit at Woodston is, as mentioned above, of a very con- 

 siderable depth and the source of its origin is apparently three-fold. 

 The lowest strata, which lie directly above the mass of rubble, consist 

 of a light-coloured, yellowish, sandy marl, stiffening in places to a 

 marly clay and containing here and there patches or pockets of a 

 black peaty silt. These strata are full ot land and fresh-water shells 

 and are quite evidently of a fluviatile or lacustrine origin. This 

 lowest bed, containing the shells, is from four to five feet in thickness. 

 Above this lies an even horizontal bed of a stiff dark clay, almost 

 black in colour and about three feet in thickness. This bed contains 

 a species of Paludestrina in great abundance, with a few fresh-water 

 shells, Limncea and Flanorbis, a few immature Hygro/nia, and a good 

 number of valves of Cardiiim edide. This portion of the deposit I 

 take to be of estuarine origin ; and Mr. A. S. Kennard informs me 

 that this bed of estuarine clay may possibly be the local equivalent to 

 the Buttery Clays which to the south and east underlie the great 

 peat deposits of the Fens. Then again above this estuarine or Palu- 

 destrina Bed lie strata of marine sands and gravels twelve to fifteen 

 feet in thickness, from which at present I have taken but one species 

 of marine shell — Scrobicularia plana. 



There can be no doubt, therefore, of the great age of the shell 

 deposit in the lower strata, for evidently at some period the sea has 

 buried the whole district, and I incline to think that we have here the 

 bed of a lake existent in early glacial times. For the molluscan fauna 

 is on the whole of a definitely Arctic type, very much akin to the 

 Scandinavian fauna of to-day and no traces whatever have been found 

 so far of either Ancylus or Neritina, such genera as one would cer- 

 tainly expect to occur in a river deposit. Moreover the old bed of 

 the River Nene (containing undoubted species of the Pleistocene 

 period) can be traced less than a mile away to the north, and one 

 can hardly conceive of two rivers, of such magnitude as their ancient 

 beds suggest, existing, so to speak, side by side. Perhaps in time as 

 fresh portions of this Buried Lake-bed are opened up in the working 

 of the clay in the immediate neighbourhood, we may discover the 



