50 Prof. Presticich — Ci/rena Jluminalis near Oxford. 



shells washed out of the Oxford Clay, such as the large Oryphea 

 dilatata, and Belemnites. There are also large rounded pebbles of 

 quartzite and other Paleeozoic rocks, but these come from an older 

 glacial drift gravel found on the summit of Wytham, Bladon and 

 other high hills, still in the same watershed. Sometimes the gravel 

 is roughly piled together, at other times it is rudely bedded, while 

 occasionally the sands present the fine lamination due to more tran- 

 quil deposition arising either from diminished force of the current, 

 or from being in more sheltered places. 



In the gravel-pits at Summertown and elsewhere around Oxfoi'd, 

 it is rare to find even fragments of shells, and only still more rarely 

 are a few perfect shells met with. But at the St. Edward's section, 

 where the beds are finer and consist chiefly of sand, owing probably 

 to their having been deposited more out of the way of the main 

 current, the shells are in places numerous, and almost all are entire 

 — some indeed are double, though they are very fragile. 



They consisted chiefly of Fisidium, Zimnea and Cyrena. With 

 one exception there was no record of the existence in this area or 

 indeed in any part of the Upper Thames Valley, of the Cyrena 

 Jiuminalis. That exception is a single specimen found some years 

 ago by Mr. Tiddeman, of the Geological Survey, in a small pit or 

 section on the banks of the Cherwell, but I have never succeeded 

 in finding this pit or section, which has no doubt been filled up or 

 sloped over. So the evidence of the occurrence in this district of 

 this particular fossil rested on that single specimen, which is preserved 

 in the Oxford Museum, In the St. Edward's section this shell has 

 again been discovered in considerable numbers — of all sizes, and 

 double, proving that it lived and flourished here at the period in 

 question. It is in fact the most abundant shell there. 



The following is a list of the various shells I have obtained from 

 the St. Edward's section : — 



Bivalves. 

 Cyrena Jiuminalis. 

 Cyclas ? 



Fisidium amnia/m. 

 TJnio (fragments only.) 



Land Shells. 

 Helix hispid'i. 



Univalves. 

 Ancylus fiuvintilis. 

 Bitliynia tentaculata. 

 Limnea peregra. 



,, truncatula. 

 Flanorbis ? 

 Valvata piscinalis. 



Together with these shells there were found some fossil bones, 

 mostly of large size, and a few teeth. Unfortunately, the bones are 

 so much decomposed and so soft, that it has not been possible to 

 preserve the specimens. One of these was the entire humerus of an 

 Elephant, but the others were indeterminable. The teeth are those 

 of ZJlepJias primigenius, one specimen is almost perfect and but little 

 worn, whereas the other is worn down to a mere stump. Similar 

 remains of the Mammoth are extremely abundant in the gravel 

 under Oxford ; the lower jaws of five or six individuals having been 

 found in digging the foundations of the New Schools, and nearly as 

 many more in making the Drainage works at Holywell. 



In the adjacent Summertown brick-pit, the same gravel contains a 



