226 PKOF. .T. £. MABB C» T THE [vol. LxXV, 



The following mollusca from this loam of the upper series were 

 collected by Mr. C. E. Gray, and determined by Mr. Kennard : — 



Pupilla muscorum Linne. j Succinea pfeifferi Rossmassler ? 



Vertigo parcedentata A. E. Braim. i Lvmnsea palustris Miiller. 



Vertigo edeutula Draparnaud. i Lvmnsea truncatula Miiller. 



Vertigo antivertigo Draparnaud ? i Pisidium nitidum Jenyns. 



Succinea oblonga Draparnaud. 



The height at the top of the ground at the well was determined 

 by Mr. P. Lake to be 35 feet 6 inches above sea-level. 



The section at Barnwell-Station Pit lias been described in a 

 paper by Miss E. W. Gardner & myself, 1 and we called attention 

 to the existence of peat- seams with an Arctic flora. In that paper 

 attention was drawn to the fact that the deposits extend below 

 the alluvium of the Cam. and that they were probably accumulated 

 in a buried channel. There is evidence that, at the time of the 

 existence of this buried channel, the diversion of the drainage 

 from Cambridge to Somerham to its present direction past Ely 

 occurred, and not at an earlier date. A discussion of this matter, 

 however, requires a description of deposits a way from the immediate 

 neighbourhood of Cambridge and must be deferred to another 

 occasion. Both pl^sical and palaeontological evidence point to 

 these deposits of Barn well-Station Pit being the newest Pleistocene 

 deposits of the neighbourhood of Cambridge, having apparently 

 been deposited in a partly-buried channel below the level of the 

 present Cam alluvium. 



The probable existence of this channel is also indicated by the 

 deposits mentioned by Prof. Hughes in his paper on ' The Gravels 

 of East Anglia.' He states (p. 40) that 



"* the Jesus College gravel with Mammoth runs to a depth of some 30 feet 

 below the lower end of Maid's Causeway,' 



which is almost flush with the top of the alluvium of Midsummer 

 Common. 



I had hoped that the late Mr. Clement Reid would have 

 described the flora of the peat from this pit ; but he died before he 

 had completed the study of the plant-remains. He furnished a 

 provisional list of the plants, which is here given. The specimens 

 were washed from the matrix bv Miss E. W. Gardner. 



Thai ict rum alpinum Linne. 

 Ranunculus hederaceus Linne. 

 "Ranunculus lingua Linne" ? 

 Ranunculus repens Linne ? 

 Ranunculus bulbosus Linne. 

 Draba incana Linne. 

 Viola palustris Linne. 

 ■Silene coelata Reid. 

 Linum prsecursor Reid. 

 Rubus sp. 



Potent ilia e recta Hampe. 

 Potent ilia anserina Linne. 

 Hippuris vulgaris Linne. 

 Myriophylhim spicatum Linne. 



Carpinus Betulus Linne. 

 Salix lapponwm Linne. 

 Salix cinerea Linne. 

 Salix repens Linne. 

 Salix herbacea Linne. 

 Salix reticulata Linne. 

 Sparganium minimum Fr. 

 Potamogeton heterophyllus Schreber. 

 Potamogeton densus Linne. 

 Potamogeton obtusifolins Mertens & 



Koch. 

 Eleocharis palustris Rcemer & 

 Scirpus sp. [Schultes 



Carex incurva Lightfoot. 



Armeria arctic a Wallr. ! Carex vulpina Linne P 



Menyanth.es trifoliata Linne. ! Carex sp. 



Betvla nana Linne. j Isoetes lacustris Linne. 



Geol. Mag. dec. 6. vol. iii (1916) p. 339. 



