in the Neighbour hood of Edinburgh. 225 



Another kind of food afforded to the lesser finny inhabitants 

 bf 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 Buckland 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. Agassiz writes tome, 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 Mantell 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, 1 ' 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. f f 



