in the Neighbourhood of Edinburgh. 225 
Another kind of food afforded to the lesser finny inhabitants 
of primeval rivers or lakes, must of necessity have consisted in 
the droppings from larger animals, or even in the putrid carcasses 
of such fish as died in the waters. In these cases, numerous little 
scavengers (as Dr Buckianp calls them) would not allow putrid 
and insalubrious matter to remain long undevoured. 
It would thus appear, that while the impurity of ancient 
waters was thus obviated, an excess of increase was checked by a 
mutual system of voracity. 
NOTES TO SECTION XV. 
M. Acassiz writes to me, that he has been making observations on the organs of 
digestion possessed by the large monsters belonging to later formations. He found 
that a very singular body, which Mr Manette had taken for the swimming bladder 
of the Macropoma, was in reality its stomach, the different membranes of which were 
well preserved, yet were liable to exfoliation when long in contact with the air. At 
the posterior extremity of the alimentary tube, coprolites might be detected, round, 
like those of the reptiles of Lyme Regis, and containing scales of the Zeus Lewesiensis. 
“ Who would have formerly presumed,” he asks, “ to one day find in the fossil state 
organs of digestion with all their forms preserved ?” 
SECTION XVI—THE MODE IN WHICH VEGETABLE AND ANIMAL REMAINS 
ARE DIFFUSED THROUGH THE LIMESTONE OF BURDIEHOUSE. 
The sequel of this portion of the present memoir will be de- 
voted to a few remarks on the mode in which the vegetable and 
animal remains of Burdiehouse are diffused through the lime- 
stone. 
In this diffusion, little or no order is preserved. Vegetable 
and animal remains are not confined to particular seams of the 
rock, but may occur in any part of it. Nor are they confined to 
the limestone itself, since they have been found in argillaceous 
and bituminous shale, both above and below the bed. And if 
they are discovered in much greater number in the limestone, the 
excess may, in some little degree, be owing to the far better state 
of preservation in which organic remains are preserved in a cal- 
careous matrix. At the same time, the circumstance must not be 
lost sight of, that ancient waters, in which calcareous matter was 
VOL. XIII. PART I. Ff 
