180 Geological Society. 
November 25, 1891.—Sir Archibald Geikie, D.Se., LL.D., F.R.S., 
President, in the Chair. 
The following communication was read :— 
“On the Os pubis of Polacanthus Foi.” By Prof. H. G. Seeley, 
ERS., EGS. 
Hitherto the evidence of the systematic position of Polacanthus 
has not been very precise. ‘lhe Author has detected the missing 
pubis as an isolated specimen. ‘This he regards as the anterior por- 
tion of the left pubis, and appends a full description of the bone. 
He furthermore gives a critical account of our knowledge of other 
pelvic bones of the genus, and is led to associate Agathawmus, 
Crateomus, Omosaurus, and Polacanthus in near alliance, in the 
Scelidosaurian division of the Order Ornzthischia. 
December 23, 1891.—W. H. Hudleston, Esq., M.A., F.R.S., 
Vice-President, in the Chair. 
The following communication was read :— 
“On Part of the Pelvis of Polacanthus.”” By R. Lydekker, Esq., 
BoA. F.G.8: 
The specimen described in this paper was acquired by the British 
Museum from the collection of the late Mr. Beckles, and is from the 
Wealden, probably of the Isle of Wight. It is the central part of 
a Dinosaurian ilium, with portions of sacral ribs attached. 
The point of special interest is a flat plate ef bone, evidently a 
portion of dermal armour, resting on the upper border of the ilium ; 
and this suggests comparison of the specimen with the dorsal shield 
of Polacanthus Fouti. Such a comparison shows that the present 
specimen belonged to a Dinosaur closely allied to, if not identical 
with, P. Fowit. 
January 6, 1892.—W. H. Hudleston, Esq., M.A., F.R.S., 
Vice-President, in the Chair. 
The following communications were read :— 
1. “Onanew Form of Agelacrinites (Lepidodiscus Milleri, n. sp.) 
from the Lower Carboniferous Limestone of Cumberland.” By G. 
Sharman, Esq., and E. T. Newton, Esq., F.G.S. 
Among a large series of fossils obtained during the Geological 
Survey of Cumberland and Northumberland, there are two which 
are referable to that remarkable and rare group of Echinoderms, 
the Agelacrinitide. The more perfect of these specimens is from 
the Lower Carboniferous rocks near Waterhead, on the River 
Irthing, and forms the subject of this communication. The disc- 
like fossil is only about four-tenths of an inch in diameter, and 
scarcely rises above the shell to which it is attached ; nevertheless, it 
is so Well preserved as to allow much of its structure to be studied. 
It is referred to the genus Lepidodiscus, and is seemingly closely 
