﻿lxxxii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [vol. lxxii, 



June 7th, 1916. 



Dr. Alfred Harker, F.R.S., President, 

 in the Chair. 



The List of Donations to the Library was read. 



Dr. F. L. Kit chin, M.A., F.G.S., exhibited a representative set 

 of Mesozoie fossils obtained from deep borings and 

 pit -sinking's in Kent. The specimens were selected from the 

 collections of the Geological Survey; by permission of the Director. 

 The life of the successive zones present in the various sections was 

 illustrated by the arrangement of the specimens in sequence, the 

 series comprising a time-range from the Lower Lias up to the top 

 of the Lower Greensand. The section revealed in the Brabourne 

 Boring is remarkable for the range of formations found there in 

 superposition, and may be regarded as the type-section for the 

 study of the hidden Mesozoie succession in Kent. Specimens were 

 exhibited from that locality and from the shafts at Dover, but 

 these were supplemented by materials obtained more recently from 

 various borings situated east of a line drawn from Folkestone to 

 Canterbury. 



The speaker described the principal characters of the faunas' as 

 developed in this area, and made incidental references to the nature 

 and distribution of some of the associated rock-types. At some 

 horizons, the molluscan assemblage assumes a particular aspect, by 

 reason of the preponderance of species fitted for life amidst the 

 special conditions of deposition. On the other hand, there are 

 evolutionary phases which recur repeatedly with considerable uni- 

 formity, and seem to arise independently of immediate surrounding 

 conditions. Such are illustrated by the degenerative changes 

 shown to occur in many ammonites, and by some of the forms 

 repeatedly assumed by the members of separate series among 

 Mesozoie oysters* 



The evidence of ammonites, so important for the purpose of 

 zonal determination, is frequently forthcoming at these localities 

 in Kent, even in borings of narrow diameter ; but it is often 

 necessary to rely entirely upon the aid afforded by the more 

 abundant bivalves. Many of these, although belonging to un- 

 described species, are found to have a limited vertical range, and 

 by their distribution throughout this area, as well as farther afield, 

 prove of much service in these correlation-studies. Specimens of 

 many undescribed species have come to light, as well as others 

 which are known from their occurrence in Continental localities, 

 though not previously recorded in this country. 



A small series of Jurassic Cephalopoda from Kachpur (Russia), 

 collected by the late G. F. Harris, F.G.S., at the time when the 

 International Geological Congress met at Petrograd (1897), was 

 exhibited by James Francis, F.G.S. 



