306 Royal Society : — 



opinion is fonnded npon tlie previous examination many years ago of 

 the mode then used for making gun-flints. 



Amongst the many vahiable observations of Dr. Falconer, one 

 fact to which he testifies deserves the most marked attention, 

 and may possibly assist in directing us to the true solution of the 

 problem. 



Dr. Falconer has noticed the fact that the greater portion of these 

 bones belong to the Hippopotamus, and also that they occur in their 

 several deposits in enormous numbers. In each cave there must 

 have been several thousands, if not tens of thousands, of individuals. 

 The question immediately suggests itself, what causes produced this 

 vast collection of individuals of the same race entombed in one 

 common sepulchre ? 



It is scarcely possible to suppose that any instinct could have led 

 the Hippopotamus, when death approached, to have chosen particular 

 spots where the bones of his race were exposed to his view. If this 

 were so, then most probably the existing race would possess the same 

 instinct. 



Another question arises : Were these remains originally deposited in 

 different localities, and afterwards transported by some common cause 

 to these various caverns and beaches ? Water seems the only probable 

 mode of conveyance : if this were so, traces of the rolling action of 

 water must be found on all the bones, but this I apprehend is not 

 the case. Moreover, it is difficult to conceive how water could have 

 collected the bones of a multitude of individuals of the sa7ne race, 

 distributed over a wide extent of country, into a few fiivoured 

 localities. The bones of all other animals inhabiting the same 

 couutry, and remaining on its surface, would have been exposed to 

 the same action, and should have been deposited in the same tomb. 

 If these animals all perished at the same time in each locality, some 

 common cause must have produced the catastrophe. 



Although the existing evidence may be insufficient to lead us to 

 the true solution of this interesting question, yet it may be useful to 

 throw out hypotheses, which, by accounting for some of the facts, 

 shall direct the attention of future observers to the examination of 

 such special points as may either partially support or directly dis- 

 prove these conjectures. 



With this view I shall offer two conjectures, one dependent on the 

 subsidence of the land, the other upon the rising of the waters. 



Conjecture I. — By the subsidence of the land. 



Let us imagine that the basin of the bottom of the Mediterranean 

 had at a former period been on a level with, or just above the 

 African continent. Sicily and the various islands would then have 

 stood above it as mountain chains. 



One portion of the drainage of this laud may have been effected 

 by a vast river passing into the Atlantic through the opening now 

 known as the Straits of Gibraltar. 



In this state of things extensive freshwater lakes and other large 

 rivers may have contributed to sujjport large herds of Hippo- 

 potami. 



