THE AVONIAN OP THE AVON GOROE 
75 
of the generic names which recur most frequently in the text ; 
the section devoted to this purpose is intended for the use of the 
student only, since its necessary incompleteness will render it 
unsatisfying to the specialist. 
Again, since the paper deals mainly with the establishment 
and analysis of the faunal succession, it has been necessary 
to introduce a brief statement of the biological principles upon 
which the zoning of the Lower Carboniferous Rocks has been 
carried out, and also to point out certain fundamental pheno- 
mena which characterize faunal variation. 
Lastly, since this manual is confessedly a compilation, I 
have seen no reason for nicely allotting the credit for each fact, 
and for each law, to its first discoverer. 
^ It would be a laborious, if not an unprofitable, task 
to collect all the references which have been made 
by earlier writers to the rocks and scenery of the Avon Gorge. 
I shall consequently content myself with references to the work 
of those few geologists who have examined the section systemati- 
cally, and with the purpose of some definite line of research. 
Nearly a century ago, in a paper entitled ‘ On the Limestone 
Beds on the River Avon, near Bristol,’^ George Cumberland gave 
a minute description of each bed in the Avon Section and, 
although the old-time terminology sounds strange, it is not 
difficult to recognize certain of the best known horizons from 
the writer’s descriptions. 
Some sixty years later, ^ W. W. Stoddart undertook a 
detailed examination of the Carboniferous Limestone Series of 
the Avon, with the view of compiling an exhaustive record of 
the fossils found in each bed. An analysis of Stoddart’s paper, 
in so far only as it deals with Corals and Brachiopods, will be 
found, set forth at considerable length, in my paper on the 
Bristol Sequence.^ 
1 Geol. Trans. (1811 and 1818). 
^ Proc. Bristol Nat. Soc. n.s. vol. i. (1875), p, 313. 
^ Quart. Journ. Geol. Soc. (1905), vol. Ixi. p. 200 
