500 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 25, 
of appreciable size. The box-stones are to be found in some quantity 
on the beach at Felixstow, having been washed out of the cliffs, and 
are also to be seen in the so-called “coprolite diggings.” They 
occur in the ‘ bone-bed”’ which is exposed in these diggings, and 
are picked out by the workmen, together with flints and a few 
other pebbles, from among the smaller phosphatized-clay fragments, 
and are thrown into heaps by the side of the diggings, when they 
are sold as ‘‘metal” for the roads. With one exception all the 
masses of sandstone I have seen thus picked out from the diggings 
have been spherical, oblong or irregular masses about the size of the 
fist, on an average, or sometimes of an elongated cylindrical form. 
The exception was in a pit at Trimley, near Ipswich, where I found 
four blocks of a flagstone shape about a foot and a half square, 
which contained casts of shells, and seemed to be identical in origin 
with the box-stones. 
It is important to ascertain whether these “‘box-stones” are all 
of the same age, whether any of them may be masses of Kocene, or 
even Cretaceous sandstone. After examining a vast number of them, 
I believe them all to be rolled masses of the same arenaceous deposit 
and of Diestien age. Some of them have a very decided green tint, 
and vary in the darkness of this coloration. This coloration recalls 
strongly the black sands of Antwerp, to which it appears they are 
related, and is due to the same glauconitic constitution. Others of 
the nodules have a dark reddish-brown tint, particularly those from 
the sea-beach, and this change of colour is, no doubt, due to the 
higher oxidation of the contained iron. Lithological evidence is 
entirely in favour of the community of origin of these rolled masses 
of sandstone, the only doubtful specimens being those from the pit at 
Trimley above mentioned. Amongst the stones separated from the 
“coprolites” by the diggers, fragments of Liassic and of Cretaceous 
rocks are to be found, but very rarely. There is no chance, it will be 
admitted on inspection of the specimens, of confounding derived 
greensand specimens with these box-stones. 
The box-stones, being of very porous constitution, are constantly 
subject to the action of infiltering water, and consequently those 
which contain shells have, with very rare exceptions, been deprived 
of the calcareous matter of the shell; consequently on breaking open 
such a ‘“‘ box-stone” with the hammer, a very perfect natural cast of 
the interior of the shell is obtained and also a concave cast of the 
exterior. Under these circumstances identification of the species of 
enclosed mollusca is exceedingly difficult ; for even skilled concholo- 
gists are not apparently familiar with the appearance of internal 
casts of the various species which they study. A very useful plan, 
in those cases which allow it, I have found to consist in taking 
gutta-percha impressions of the concave casts; in this way a perfect 
restoration of the original shell is obtained, and conclusions formed 
from the internal casts may be corrected. In this way I have got 
very beautiful impressions of a Conus (Plate XXXIV. fig. 5) (first 
observed by Mr. Searles Wood in these nodules), also of a small Cas- 
sidaria (Plate XXXIV. figs. 8, 9), which has been hitherto regarded 
