BONES OF MICE, 93 
there is a diminished quantity of the albuminous 
substance, thoughit may not appear so. Mr. Martyn, 
in his“Treatise on Fossils,” speaks cautiously on the 
subject of the chemistry of fossil bones by saying, 
through Professor Playfair, that they often contain 
a portion of gelatin (or rather, by recent examina- 
tion, albumen) in their composition, particularly in 
their interior, the surface only having undergone a 
change. In other instances, he adds, the gelatin 
(albumen) is wholly displaced, while a greater pro- 
portion of carbonic acid than that which existed in 
it originally is found united with the calcareous 
matter. Those in the Rock of Gibraltar seem to 
have been so circumstanced. It seems from Professor 
Buckland, that the bones at Oreston contained less 
of albumen than those at Kirkdale. The question, 
therefore, respecting the composition of fossil bones 
must be answered in a cautious and qualified 
manner, and with reference to the conditions of 
each particular case. 
The occurrence of the bones of mice in the sub- 
stance of some of the stalagmite, is a circumstance 
to which too much attention cannot be directed in 
framing a theoretic statement of the age of the con- 
tents of this cavern, because, as before mentioned, 
they are not identically the same species with those 
now in existence, and from their peculiar position 
might seem not to have been contemporary with 
the other animals. Yet, in consideration that other 
specimens of these remains were discovered in the 
diluvial clay, it may not be unfair to suppose that 
these found in stalagmite were so impacted pre- 
viously to the catastrophe which effaced the whole 
series of antediluvian creatures, during indeed that 
period in which the hyenas and other predatory 
beasts employed this cavern, or its compartments, 
as their dens. There is the same analogy or re- 
semblance of these mice to the present kinds, as 
