Yol. 50.] OSSIFEROUS FISSURES NEAR 1GHTHAM. 187 



relations of stratification and filtration would have been obliterated ; 

 this, however, we know was not the case. 



Attention might also be called to the fact that the bank on the 

 top of the fissures became an old Neolithic settlement, neoliths 

 being scattered over the surface literally in hundreds, yet not one 

 of these was found in the fissure. 



It is true that the mollusca might have borne a more aquatic 

 facies, and not much can be said from a solitary entomostracon, 

 but I have worked for many months at a river-deposit in which 

 there were myriads of these little creatures, and only found one 

 gasteropod, nor do any of the more aquatic forms occur in any 

 deposit which I have worked in the valley outside. 



We have, however, I think, far more evidence both positive and 

 negative than we could reasonably have expected under the cir- 

 cumstances, that the fissures have never been reopened since they 

 were first closed by the materials introduced into them by the river ; 

 and although it is within the bounds of possibility that in some 

 unknown and incomprehensible manner some stray modern relic has 

 been introduced, and in each case by some remarkable modification 

 of chemical laws has been changed into a condition indistinguishable 

 from those upon which the same forces have been operating for 

 countless ages, there is still the great balance of probabilities that 

 the whole of the contained fossils belong to one and the same 

 geological period. 



I am fully aware that there are many remains found here which 

 have not been found before in recognized Pleistocene deposits ; but 

 that has been my experience with other sections at which I have 

 worked for a long time. The increase in species is only such as to 

 support the suggestions made by Mr. Clement Reid in connexion 

 with the Forest Bed fauna, 1 namely, that late discoveries tend to 

 show that it is the larger Pleistocene mammalia that have become 

 extinct, and that the more we discover of the smaller creatures of 

 this age, the more they approximate to those of our own time. 



Even if we were to exclude from the lists all the species not 

 previously found fossil elsewhere, we still have an extensive 

 assemblage of the older Pleistocene forms which must have lived 

 during the filling of the fissure : this therefore limits the filling 

 operation to Pleistocene times. 



In conclusion I have to express my hearty thanks to the officers 

 of the Geological Survey, especially Messrs. Clement B-eid, H. B. 

 Woodward, and W. Topley, for the very great assistance which I 

 have received from their invaluable advice, while it is unnecessary 

 to remark that the chief value of the paper hinges upon the work 

 bestowed by Mr. E. T. Newton upon the vertebrates. I have also 

 to thank Mr. B. B. Woodward for his kind assistance in the deter- 

 mination of the mollusca, and Mr. C. 0. Waterhouse for naming 

 the insects. 



[For the Discussion on this paper, see p. 210.] 



1 Mem. Geol. Surv. 1890, ' The Pliocene Deposits of Britain,' p. 182. 



o2 



