78 CONSECUTIVE DEPOSITIONS. 
I have said that a strict classification of rocks 
according as they contain animal remains or not, 
is inadmissible, and, that to recognise this principle 
in drawing out a theory of the deposition and age 
of our own strata we must lose sight of plain indi- 
cations of a contrary tendency. Iam not however 
saying that “ zoological epochs” as set forth on the 
large scale are factitious or arbitrary, and I here 
revert to this opinion in order to state with candour 
that if one were inclined to favour the idea of con- 
secutive depositions of our strata, it would receive 
support from these facts : 1st—some of our strata, 
or parts of strata are devoid of fossils ; 2nd—some 
parts of the strata contain a very sparing quantity 
of the lowest tribes of animals ; 3rd—some parts of 
the slate contain a profusion of fossils, some of which 
are of a higher grade than those sparingly scattered 
in other parts of it; 4th—the limestone contains 
petrifactions of far- greater variety and generally 
higher order than those found in the slate; 5th—the 
slate contains some organic remains not found in 
the lime; 6th—I must add also, that though the rule 
is far from being universally observed, lime and 
sandstone which contain the highest organised 
remains, for the most part preserve the highest or 
most superficial position in the series of our rocks. 
Our lime is said to repose between slate on the 
north, and sandstone south, but, as I have elsewhere 
shewn, this rule is valueless. 
Whatever may have caused this curious arrange- 
ment, I am of opinion that the equally curious 
classification of bivalves, univalves, zoophytes, &c. 
one sort apart from another, as observed by the 
Rev. Mr. Hennah in the limerocks, belongs to the 
same series of phcenomena ; besides which, I am 
now enabled to add, that a partial order of this same 
nature may be noticed in our slate fossils, though, 
through ignorance of their specific names, I cannot 
here venture on an accurate account in proof. 
