Dr. Mantell’s Notice of Molluskite. 245 
you specimens. In some instances this material actually forms 
the entire casts of the univalves and bivalves, and I think there 
can be no doubt that it is derived from the soft bodies of the 
animals which inhabited the shells found in connection with it, 
fossilized in this peculiar manner. 'There are many examples 
which look more like true coprolites of fishes, and some of these 
contain shells partly crushed, as if they had been the partially 
digested contents of the intestinal canal. I am therefore inclined 
to think that the dark material which now occupies the shells, 
was the soft body of the mollusc, that those of a concretionary 
form which are imbedded in the stone are coprolites, and that 
the shapeless portions of this substance distributed in the rock 
have originated from floating masses of dead shell-fish. In illus- 
tration of the manner in which such an accumulation of mate- 
rials as I find in my quarry, may have been formed, I beg to call 
your attention to the following extract from the American Journal 
of Science for 1837, which seems to me to afford an explanation 
of some of the appearances that I have attempted to describe. 
““¢One of the most curious phenomena of the year 1836, was 
the fatal effect of an epidemic among the molluscous animals or 
shell fish of the Muskingum River, in the state of Ohio. It 
commenced in April and continued until June, destroying mil- 
lions of that great race, which peoples the beds of streams. As 
the animals died, the valves of the shells opened, and decompo- 
sition commencing, the muscular adhesions gave way and the 
fleshy portions rose to the surface of the water, leaving the shells 
in the bed of the stream. As masses of the dead bodies floated 
down the current, the headlands of islands, piles of fixed drifted 
wood, and the shores of the river in many places were covered 
with them, and the air in the vicinity was tainted with the pu- 
trid effluvia exhaling from these accumulations of decomposing 
animal matter. 'The cause of the disease among the shelly tribes 
remains as much a mystery as that of the Asiatic cholera among 
the human race.’ 
“‘ Now nearly the whole of the shells which occur in the bed of 
Kentish rag, appear to have been dead shells. I mean that from 
the open state of the valves it is probable that the animals for the 
most part, were dead before they were enveloped in the sand and 
mud; and from the large quantity of water-worn fragments of 
wood perforated by lithodomi, that is imbedded with them, it 
