604 
hugely clawed feet are very noticeable. This unique and 
very interesting little plaque or boss, formerly in Mr. Roach 
Smith's Museum of London Antiquities, is now in Mr. Roach 
Smith's Collection in the British Museum, it is, as has been 
stated, of bronze, but it contains a much larger proportion of 
copper than usual. Along with it was found a flat star- 
shaped object of similar metal arid size ; and there can be 
little doubt they had been connected by rivets upon some 
post or lintel of wood in decoration. 
Reverting to the mosaic, it only remains to notice the 
composition and colours constituting the groundwork used 
in its production. The bluish-black and the white, and the 
few yellow, tesserae, are all natural stones, the former being 
blue lias, and the latter magnesian limestone. The tesserae 
of a red colour alone are artificial, being of baked clay. 
The whole are set in a deep bed of the admirable concrete 
of the Roman architects, too well known to require 
description here. 
ON THE GEOLOGY OF THE BARNSLEY COAL-FIELD. BY A. H. 
GREEN, M.A., OF THE GEOLOGICAL SURVEY OF GREAT 
BRITAIN. 
Though I might occupy the time at our disposal with an 
account of the objects of geological interest in the immediate 
neighbourhood of Barnsley, and by no means exhaust the 
subject, I think I shall make this paper more interesting 
and instructive if I take rather a wider range, and show first 
of all the relation of the rocks we now stand upon to the 
general geology of England. 
If we draw a line from Nottingham, through Derby and 
Ashbourne, to near Trentham, then wind it up to Manchester, 
and thence to the estuary of the Mersey, this line will be the 
northern boundary of the New Red Sandstone plain of 
