exxil ANNIVERSARY MEETING. 
tending continually to the suggestion and establishment of highly 
important inferences and discoveries ; it must not be disguised, how- 
ever, that there is always more or less of difficulty in acting upon the 
principle. The first obstacle is its mapplicability to any beds that 
are not stratified —its irrelevancy to all such as are amorphous or in- 
trusive. The second obstacle is, that individual beds are seldom of 
any great extent, and that their number is so large that no one would 
ever think of dealing with them singly: to deal with them at all they 
must be thrown into groups, which, as they must be in some measure 
capricious, has led to the construction of different systems. The 
chronological table, by which Mr. Lonsdale was guided in the ar- 
rangement of the British collection, as detailed in the Report of the 
Committee in 1842, will, it is presumed, be generally acknowledged 
to have been as judicious and unobjectionable as any which could at 
that period have been devised ; and the question arises, whether it 
ought still to be adhered to in all its integrity; and, if not, what 
amount it may require of modification ? 
The leading cause of the difference observed in the several tables 
above-mentioned, results from the greater or less indulgence afforded 
to the practice of subdivision. | 
Where there is a marked change in the character of the fossils in — 
a group hitherto represented as one and the same throughout, a sub- 
division of that group is obviously required. Upon this principle the 
Crag, formerly considered as a single mass or formation, is now split 
into three. On the other hand, it must be admitted that some ad- 
vantage is to be obtained from a disposition to generalise, as well as 
from the contrary habit of running into detail, and multiplying 
distinctions. It has been well observed that few organic forms are 
monochronous—the greater number have had a range of existence 
exceeding the limits of any one chronological horizon ; many have 
extended through several successive formations, and in all these 
cases the necessary consequence of splitting up groups is to multiply 
repetitions. 
The Committee which sat in 1842 were the first to question the 
value of mineralogical characters when applied to chronology,—the 
first to point out the inexpediency of confounding in the same cabimet 
the fossiliferous specimens and the non-fossiliferous. 
A very large proportion of the fossiliferous specimens are imbedded 
in a matrix, and this matrix should of itself be sufficient, or nearly 
sufficient, to furnish to the student quite as much lithological infor- 
mation as in this department he is likely either to expect or desire. 
More detail in that branch of information could only tend to bewilder 
him. The Committee apprehend that where the necessity of intro- 
ducing lithological specimens into the British Collection ceases, the 
expediency ceases also. 
The British Collection, which has ever been the favourite one, has 
naturally enough, perhaps harmlessly, become a continually encroach- 
ing collection. Its geographical encroachment has been already 
noticed, but it may be proper also to pomt out its zoological en- 
croachments. 
