384 
THE GEOLOGIST. 
the clironological equivalents of the " Old Red" of Herefordshire and 
Scotland — much as they differ lithologically and palteontologically 
Scotland does not yield the shells, corals and sponges so abundant in 
Devonshire ; nor are the ichthyolites, with which the Scotch rocks 
teem, found in the latter district : this, however, has ceased to be 
chronological dif^culty, since the author of " Siluria" found the fossils 
characteristic of each of the areas lying together in the same Devonian 
beds in Russia.* 
It is but right to add that many geologists well acquainted wit 
the Devonshire I'ocks have accepted this chronological decision in a 
more or less modified form. Thus, the late Sir H, de la Beche 
regarded " The bulk of the Devonian and Cornish rocks as at least 
in part equivalent to the lower beds of the Carboniferous limestone, 
to the passage-beds between the Old Red Sandstone and Carboni- 
ferous limestone of Ireland, South Wales, &c., and also to some 
portion of the higher part of the Old Red Sandstones of Hereford- 
shire and adjacent districts. "t The late Rev. David Williams 
considered the Devonian system as occupying "an enormous interval 
between the Old Red Sandstone and the Mountain-limestone.";}; 
The late Mr. D^ Sharpe, Professor Jakes, and Mr. Austen, have 
advocated the view that the rocks of Barnstaple in i^orth Devon, 
and South Petherwin in Cornwall, belong to the Carboniferous 
system ; whilst Mr. Salter would modify this, and class the upper 
portion of the Barnstaple group only as Carboniferous. The chro- 
nology of the Barnstaple and Petherwin beds will again come under 
notice, when discussing the distribution of the fossils of Devon and 
Cornwall. 
That life existed on the earth during the era of the Devonian 
rocks is evidenced by the fossils they contain ; unless, with the 
author of " Omphalos," we hold them to be irrorlironic. Indeed, 
the introduction of life dates very much earlier than this, since no 
fewer than very nearly one thousand species of organisms are 
recorded as having become extinct in Britain alone, in pre-Devonian 
times. The following table exhibits the amount and variety of life 
in the period under consideration, as compared with the fauna and 
flora now existing. 
The figures in the 1st, 2nd, and 6th columns are copied from 
Bronn's " Index Palasontologicus," Quart. Journ., Geol. Soc, vol. i., 
page 44 ; and those in the 3rd, 4th, 7th, and 8th, are compiled 
from Professor Morris's Catalogue of British Fossils. It has been 
thought best to take no liberties with the originals, so that the 
authors alone are responsible for the correctness of the figures, which 
though possibly incorrect in a few cases, are on the whole the best 
that can be commanded. 
* " SUuria," 3rd Edition, page 382. 
t Mem. Geol. Survey, vol. i., p. 103. 
X Keport Royal Geol. Soc. of Cornwall (1843), p. 123. 
