Geological Society. 255 
with a small number of teeth of fishes, decapod crustacea, corals, 
and one Eehinoid. Aturia is also present. 
The number of species is large, and nearly all are new. 
By the stages reached in the evolution of Venericardia of the 
planicosta group, correlation is made with the Tejon Group of 
California; but the relation to the Wilcox and Lower Claiborne 
Groups of the Eastern and Gulf States of America is more marked, 
and is sufficient to indicate the existence of a sea-connexion 
between the Pacific and the Atlantic. There are some interesting 
resemblances to the fauna of the European Eocene. 
The Lobitos Formation is distinguished by the presence of 
foraminifera belonging to the genera Lepidocyclina and Ortho- 
phragmina. The mollusca in the lower part of the formation do 
not differ much from those in the beds beneath, though some of the 
species have undergone gradual change, with development of senile 
features. 
In the Zorritos Formation, all the species are different from 
those of the Lobitos and Negritos Formations. Miocene age 
is indicated by the similarity of some of the gasteropods and 
lamellibranchs to those of the Miocene of Panama. 
The mollusca and decapod crustacea are described by Mr. Woods; 
the corals by Dr. T. W. Vaughan; the foraminifera by Dr. J. A. 
Cushman ; and an Hchinoid by Prof. H. L. Hawkins. 
January 5th, 1921.—Mr. R. D. Oldham, F.R.S., 
President, in the Chair. 
The following communication was read :— 
‘The Lithological Succession of the Carboniferous Limestone 
(Avonian) in the Avon Section at Clifton, Bristol.’ By Prof. 
Sidney Hugh Reynolds, M.A., Se.D., F.G.S. 
Although, in addition to the late Dr. Arthur Vaughan, a number 
of authors, including Stoddart and Mr. E. B. Wethered, have 
described some of the rocks of the classical Avon section, no detailed 
account has hitherto been written. Most of the rocks of the Avon 
section can, however, be paralleled among those described by 
Mr. HE. EH. L. Dixon from Gower, and the Author finds himself in 
close agreement with Mr. Dixon in regard to their conditions of 
accumulation. In particular, the three Modiola phases (calcareous- 
lagoon phases) of Ky, ©,-S,, and the top of S, recognized by 
Mr. Dixon in Gower, are represented in the Avon section, and the 
only feature of general interest in relation to them that the 
Author’s work emphasizes is their very constant association with 
calcareous alge. Particular attention was paid to these organisms. 
The fact that the well-known ‘ Concretionary Beds’ which form so 
marked a feature of the Upper S, Zone are largely algal in origin 
