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researches of this kind, to make such a distinction, in fossil bones, 
almost always mutilated. 
We are indebted to Major Imrie for a most useful and interesting 
mineralogical description of the mountain of Gibraltar, in the fourth 
volume of the Transactions of the Royal Society of Edinburgh, p. lyi, 
the whole of which is highly worthy your examination. That which 
most particularly demands your attention I have here introduced. 
The eastern side of the mountain, mostly consisting of a range of 
precipice, terminates with a bank of sand in the Mediterranean. The 
southern extremity terminates in the sea, with a rapid slope, and forms 
Europa Point. On the Western side, this peninsula mountain is 
bounded by the Bay of Gibraltar ; and upon the North, it is attached 
to Spain by a low sandy isthmus, the greatest elevation of which, above 
the level of the sea, does not exceed ten feet ; and its breadth, at the 
base of the rock, is not more than three quarters of a mile. This 
isthmus separates the Mediterranean on the East, from the Bay of 
Gibraltar on the West. 
The principal part of the rock consists of a grey dense marble, in 
some parts of which are imbedded testaceous bodies, in a spathose 
state. As is almost always the case, where this species of rock con- 
stitutes large districts, the rock of Gibraltar is cavernous ; the caverns 
being beset with stalactitic, and other calcareous infiltrations. On the 
surface of the rock are seen pot-like holes, hollowed out by the attri- 
tion of gravel or pebbles, set in motion by the rapidity of rivers, or 
currents in the sea, some of the pebbles now remaining in them. 
From this phaenomenon, Mr. Imrie concludes, that however high the 
surface of this rock may now be elevated above the level of the sea, it 
has once been the bed of agitated waters. 
With respect to the fossil bones found in this rock, the general idea 
concerning them is, that they are found in a petrified state, and inclosed 
in the solid calcareous rock ; but these are mistakes which Mr. Imrie 
thus aims at correcting : — “ In the perpendicular fissures of the rock, 
