FOSSIL MAMMALIA 103 



these ancient animals, to say a word on the peculiar state in 

 which their bones were found in the gypsum-quarries. 



They were either entire or broken, according to the degree 

 of resistance which they opposed to the pressure of the strata 

 resting on them. The bones of the carpus and tarsus, whose 

 interior is solid, were generally found entire, except in cases 

 where they must have been mutilated previously to incrustation. 

 The femora, the tibiae, and the other long and hollow bones, 

 more especially those belonging to the larger species, were 

 seldom entire, except in the extremities, which are solid. The 

 skulls were generally broken or crushed, or but one half of 

 them frequently found. As for the skeletons, those of the very 

 small animals were almost always entire, having the ribs and 

 frequently the bones of both their sides. In the animals of 

 middle size, the ribs of one side alone were to be found, and 

 the skeletons of the very large species were almost always 

 disunited. The reason of this appears to be that a longer 

 time was necessary to incrust them with a coat of plaster of 

 sufficient thickness, while a small animal might be incrusted 

 before the tendons were rotten and the bones detached. When 

 the animal was a little large, and resting on one side, the upper- 

 most ribs had time to detach themselves from the skeleton, 

 while the under ones were in a process of incrustation These 

 bones are scarcely ever worn or rolled, which sufficiently proves 

 that they were carried from no great distance. They were occa- 

 sionally fractured, and sometimes evidently gnawed, previously 

 to being incrusted, which proves that carnivorous animals existed 

 contemporaneously with the herbivora in question. Nor are 

 they found in a state of petrifaction, but simply fossil, and 

 still preserving, after so many ages, a portion of their animal 

 substance. On analysis they were found to contain sixty-five 

 parts phosphate of lime, eighteen sulphate of hme, and seven 

 carbonate of lime, and they still had a portion of gelatine, as 

 they were blackened by the action of fire. 



It is astonishing that, in a country of such extent as that 



