388 Geological Society. 
wing found by Mr. John Pringle in core-material of purple marly 
shale, collected by Mr. T. C. Cantrill from a borehole for water at 
Wellington (Shropshire). 
The wing belongs to the genus Archimylacris, and is closely 
allied to A. lericheit Pruvost and A. dessaillyi Leriche, from 
the upper beds of the Westphalian of Liévin (Pas de Calais), 
Northern France. 
February 23rd, 1921.—Mr. R. D. Oldham, F.R.S., 
President, in the Chair. 
The following communication was read :— 
‘On Saccammina carteri Brady, and the Minute Structure 
of the Foraminiferal Test.’ By Prof. William Johnson Sollas, 
M.A., D.Se., LL.D., F.RS., F.G.S. 
In this description of S. carteri certain anomalies of its struc- 
ture described by Brady are explained as due to mineralization by 
quartz and the deposition of ‘beekite.’ The wall of the test, 
which is very thin, consists of a mosaic of calcite and (in its present 
state) is imperforate. 
In endeavouring to establish its true nature an investigation was 
made into the composition and structure of-the test in the Vitreous 
and Porcellanous Foraminifera. It was found that in both groups 
an organic basis is absent, and that the substance of the test 
consists wholly of calcite. The distinctive difference lies in the 
granular and felted structure which characterizes the Porcellana : 
as a consequence of this structure they are white and apparently 
opaque, any light which enters the test being scattered and 
dispersed by repeated internal refraction and reflection. 
It is shown that many Carboniferous foraminifera, such as 
Fusulina, unite the perforations of the Vitrea with the porcellanous 
test of the Imperforata; while a living in:perforate form ( Cornu- 
spira) possesses a test which in some species is porcellanous, in 
others arenaceous (Amnodiscus), and in yet others vitreous (Sp77?- 
lina), but in the last case with the exceptional character that the 
calcite test is often optically a single homogeneous erystal. 
Perforate foraminifera and porcellanous forms as well occur in 
association with Saccammina, and these still retain the original 
structure of their tests, a structure in both cases wholly different 
from that of Saccammina; the structure of Saccammina is not 
inconsistent with that of the arenaceous foraminifera, and thus one 
is led to assign this fossil to the group originally proposed for it by 
Brady. 
