part 1] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. XCIX 



April 18th, 1917. 



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

 in the Chair. 



The List of Donations to the Library was read. 



The following communication was read : — 



' TheDeveloj^ment and Morphology of the Ammonite Septum.' 

 By Prof. Henry Hurd Swinnerton, D.Sc, F.G.S., and Arthur 

 Elijah Trueman, M.Sc. 



Specimens used in the investigation of the relationship between 

 septal sections and stages in the sutural development of Ammonites, 

 as also the instrument designed for taking measurements, were 

 exhibited by Prof. H. H. Swinnerton, D.Sc, F.G.S., and A. E. 

 Trueman, M.Sc, in illustration of their paper. 



A series of Ammonites, some in section, and others ground to 

 show the form of the edges of the septa, were exhibited bv W. F. 

 Gwinnell, B.Sc, F.G.S. 



May 2nd, 1917. ' 



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

 in the Chair. 



The List of Donations to the Library was read. 



The following communications were read : — 



1. ' Supplementary Notes on Aclislna De Koninck, and Acli- 

 80 ides Donald, with Descriptions of New Species.' By Jane 

 Longstaft' (nee Donald), F.L.S. (Communicated by Dr. Gr. B. 

 Longstaff, M.A., F.G.S.) 



2. ' The Microscopic Material of tlic Bunter Pebble-Beds of 

 Nottinghamshire and its Probable Source of Origin.' Bv Thomas 

 Harris Burton, F.G.S. 



Specimens of AcUslna and Aclisoules were exhibited bv 

 Mrs. Jane Longstaft", F.L.S., in illustration of her paper. 



Lantern-slides and microscope-slides of pebbles and sands from 

 the Bunter Pebble-Beds of Nottinghamshire were exhibited bv 

 T. H. Burton, F.Gr.S., in illustration of his paper. 



There was also exhibited a geological map of Dublin, on the scale 

 of 6 inches to the mile, 1917 — presented by the Geological Survey 

 of Ireland. 



