Geological Society. 483 
PROCEEDINGS OF LEARNED SOCIETIES. 
GEOLOGICAL SOCIETY, 
January 7th, 1920.—Mr. G. W. Lamplugh, F.R.S., 
President, in the Chair. 
The following communications were read :— 
1. ‘On Syringothyris Winchell, and certain Carboniferous 
Brachiopoda referred to Spiriferina D’Orbigny.’ By Frederick 
John North, B.Se., F.G.S. 
This paper is the outcome of a suggestion made in 1913 by 
Prof. T. F. Sibly, who pointed out the desirability of an attempt to 
remove the uncertainty which had hitherto existed in the naming 
of the British species of Syringothyris, and of the Carboniferous 
Spiriferids possessing a lamellose surface ornament, which it was 
customary to refer to Spirifering because there was no other genus 
for their reception, although it had long been recognized that few, 
if any of them, really belonged to that genus. 
After indicating the exact sense in which certain frequently 
oceurring terms are used, and reviewing the history of previous 
research, the Author discusses the history in Avonian times of the 
genus Syringothyris, and suggests a classitication of its species. 
Variations due to time, to environmental conditions, and to 
distribution in space, are recognized, and distinctive names are given 
to the mutations characteristic of certain horizons. 
The syrinx (it is suggested) was a special arrangement called 
into existence to control the direction of, and to support the 
adductor-muscles, as the area of the shell increased in height. It, 
and the transverse plate to which it was attached, originated as a 
modification of an apical callosity such as existed in many Spiri- 
feroid shells. It was initiated in Middle Devonian times, and 
reached its aeme early in the Carboniferous Period. 
All known species of Syringothyris have the fold in the brachial 
valve, and the sinus in the pedicle-valve, smooth. Species such 
as S. distans, in which the fold and sinus are plicated do not 
possess a syrinx, and are incorrectly referred to Syringothyris. 
The form described by McCoy as Spirifera laminosa is referred 
to a new genus, since it has neither the punctate shell-structure of 
Spiriferina, nor the internal characters of Syringothyris. The 
genus is represented in the Tower Avonian by mutations of the 
species Jaminosa McCoy, and in the Upper Avonian by the species 
subconica Martin. 
Syringothyris and Spiriferina are in no way related, either 
morphologically or phylogeneticaily. 
The small Carboniferous shells that have hitherto been referred 
