part 3] SfOLLTTSCA FROM THE CAMBRIDGE GBAVEL8. 



235 



There can be no doubt that this deposit is of the same age as 

 that at Barnwell Abbey, For the lists are nearly identical, the 

 numerical superiority of the latter having arisen from the fact that 

 far more collecting was done there. 



Downing Section. 



During the war military trenches were dug about 150 yards 

 from the Sedgwick Museum, and, seeing the importance of the 

 sections exposed, they were deepened through the efforts of Prof. 

 J. E. Marr. The section exposed was as follows: — 



(1) Surface-soil 



(2) Warp 



(3) Buff sandy loam 



(4) Fairly coarse gravel 



(5) White marly clay 1 to 1 5 



(6) Fine gravel 2 



Feet. 

 1 



2* 

 3 

 2 



The shells occurred in two distinct horizons : one at the top of 

 No. 3, and one near the top of No. 5. We are indebted to Prof. 

 Marr for the above details, and for the opportunity of examining 

 the specimens. The upper layer yielded : — 



Papilla musconom (Linne). Common. 

 ? Vertigo antivertigo (Draparnaud). 



One example. 

 V. parcedentata (Al. Braun). Five 



examples. 

 Columella edentula (Draparnaud). 



Two examples. 



?8uccmea pfeifferi'RoasmaasleT. Four 



examples. 

 S. oblonga Draparnaud. Common. 

 Limnaea palnstris (Miiller). Common. 

 L. tnmcatula (Miiller). Common. 

 Pisidvwm nitidum Jenyns. One valve. 



An apparently recent example of the burrowing species Ccecili- 

 oldes acicula (Miiller) also occurred. 



The lower horizon furnished six species, namely : — 



Hygromia hispida (Linne). Two Sphaerium comewm (Linne). One 



examples. valve. 



Valvata piscinalis (Miiller). Four Pisidvwm a/m/mev/m (Miiller). One 



examples. valve. 



Corbicida fluminalis (Miiller). One P. hensloiranum (Sheppard). One 



valve. valve. 



This is perhaps the most important section in these gravels, 

 since stratigraphical evidence is available to check paheontological 

 conclusions. The lower horizon is clearly of the same age as 

 the Barnwell- Abbey bed; but the facies of the Upper one has no 

 exact parallel in the neighbourhood. It is probably later than 

 the upper bed at Barrington, though earlier than that at Barnwell 

 Station. 



