236 ME. A. S. KEXNAED & ME. E. B. WOODWAED 0>~ [vol. lxxv, 



Trumpington. 



We are again indebted to Prof. Marr for the details of this 

 section, and for the opportunity of examining the mollusca, which 

 are now in the Sedgwick Museum. The shells were obtained from 

 the bottom of the section, at a depth of 11 feet. Eleven species 

 are represented, namely : — 



Helicella itala (Linne). Common. Succi)iea oblonga, Draparnaud. Two 



H. crayfordensis Kennard & B. B. examples. 



Woodward. Common. Valvata pisciiialis (Muller). Two 



?H. striata (Muller). One example. examples. 



Hygromia Itispida (Linne). Common. Pisidium amnicum (Muller). Six 



Arianta arbustorvm (Linne). Six ex- I valves. 



amples. ' P. henslowanum (Sheppard). One 



Helix nemo ralis Linne. One fragment. valve. 

 Suceinea pfeirferi Bossmassler. One 



example. 



These shells would indicate that the lowest bed is contemporaiy 

 with the Barn well- Abbey gravel, or possibly a little later in age. 



Barnwell Station. 



In 1888 Mrs. Hughes described and figured the section exposed 

 in the gravel -pit near Barnwell Station, 1 and mentioned eighteen 

 species of mollusca. She discussed the relative ages of this deposit 

 and of the Barnwell- Abbey gravel, and concluded : 



• The lie of the ground seems to point to their being part of the same mass, 

 but the character of the deposits seems to indicate that, though they belong 

 to approximately the same age, they were nevertheless laid down under some- 

 what different conditions.' 



The published list of the mollusca would appear to support this 

 view, except that Mrs. Hughes notes that Papilla muscorum 

 | =JPuj)a marginata] is very common, a feature which, as we now 

 know, characterizes a much later stas^e than that of Barnwell 

 Abbey. 



In 1916 Prof. Marr & Miss E. W. Gardner described the 

 sections, which had been greatly enlarged since the previous paper. 

 They recorded four species of mollusca, and from palseobotanical 

 evidence concluded that this gravel was of the same age as the 

 Arctic Beds at Ponders End. 2 In the following year Prof. Marr 

 again referred to this pit, and emphasized its late Pleistocene age. 3 

 We had previously seen, through the courtesy of Mr. J. Wilfrid 

 Jackson, molluscan remains from ' Barnwell ' which included 

 examples of Columella columella (Gr. von Martens), a species 

 characteristic of the late Pleistocene (Arctic Beds), and we had 

 concluded that the Barnwell gravels represented more than one 

 horizon, a conclusion which was now verified. 



1 Geol. Mag. dec. 3, vol. v, p. 196. 



2 Ibid. dec. 6, vol. iii, pp. 339-43. 



3 Proc. Phil. Soc. Camb. vol. xix. pp. G4-71. 



