Dr. Nils Olof Hoist — The Ice Age in England. 435 



3. Ilford. — Eulota \_Helix~\ fruticum and Paludestrina [Hydrobia] 

 marginata, which latter is also found in 1 and 2. Both are wanting 

 in the following. 



4. Erith-Crayford. — Corbicula fluminalis, which is found also in 

 2 and 3, together with Pisidium astartoides, which is also found in 

 1, 2, and 3. Both are unknown from younger layers. 1 



These four pre-glacial occurrences are particularly interesting, 

 since they show how one warmth -loving mollusc after the other 

 disappears from the Thames Valley in proportion as the inland ice 

 approaches ; and the most warmth-loving as a rule disappears first. 

 One of the earliest is Vivipara \_Paludina] diluviana, which thus 

 proves itself to be a distinctly pre-glacial shell, and even if found in 

 a slightly later bed would still be pre-glacial. F. "Wahnschaffe, 

 therefore, as already remarked (p. 420), was completely right when, 

 in 1893, he regarded this mollusc in the same way and called the 

 Paludina-hed of Berlin pre-Glacial. 



Of the four occurrences mentioned above, that of Erith- Cray ford is 

 the most interesting. It is the last in order and therefore that which 

 came nearest to the Ice Age. None the less, it is certainly pre-glacial 

 in this sense, that in England no earlier glacial epoch has ever been 

 demonstrated or, we may be sure, ever will be demonstrated. 



The molluscan fauna of Erith-Crayford, taken as a whole, is 

 persistently temperate and pre-glacial, as is sufficiently proved by the 

 presence of Corbicula fluminalis. Planorbis arcticus, however, has 

 already come in, and Pupa muscorum has already become numerous. 



At the same time, the more mobile mammals show more clearly 

 than the two molluscs last mentioned that the inland ice is approaching. 

 In the Crayford Bed are found Ovibos moschatus, Lemmus (two species), 

 Spermophilus (here for the first time in England), Microtus \_Arvicola~] 

 ratticeps, Rhinoceros tichorhinus, and Elephas primigenius, which is 

 abundant, while E. antiqxius has now become rare. Hippopotamus, 

 which is already rare at Ilford and there perhaps only derived, has 

 now wandered southward for good. It is the approaching inland ice 

 which drives the northern animal before it. 



Thus the mammalian fauna of Erith-Crayford shows precisely the 

 same stage as the Campinian at Hofstade in Belgium. And I propose 

 that this interesting and important stage should receive the name 

 Campinian also in England. 



The molluscan fauna, however, taken by itself, apart from the 

 mammalian fauna, is quite enough to give the deposit of Erith- 

 Crayford its true place, as appears from the following. My list of 

 Mollusca from the Campinian of Hofstade is in large part new and 

 not yet published, but when I showed this list to Mr. Kennard and 

 asked him as to its English equivalent, he replied without the least 

 hesitation, "That's Crayford." 



Besides the molluscan and mammalian faunas, the Palaeolithic finds 

 also contribute to determine with certainty the correct period of 

 Erith-Crayford. In the lower part of the Crayford Bed Mr. Brice 

 Higgins — and others before him — has recently found Mousterian 



1 A. S. Kennard & B. B. Woodward, 1905. "The Extinct Postpliocene 

 Non-marine Mollusca of the South of England " : S.E. Nat., 1905, pp. 14-24. 



