BRITISH ASSOCIATION MEETING AT CAMBEIDGE. 457 
and the red sandstones of South Wales, although each deposited within 
the same great period, are not strictly contemporaneous, but were formed 
at different parts of the period. Or it is possible the red sandstone series 
of South Wales is not a continuous series ; that the lower part of it, at 
all events, is older than any of the Devon series, while the upper part 
may be newer than much of that series."* 
That some — that much — diversity of opinion should exist, respecting the 
time relations of the two systems of rocks now under notice, is what 
might be expected when their lithological and palseontological dissimi- 
larities are remembered; the northern beds are eminently arenaceous, whilst 
those in the south are almost exclusively argillaceous or calcareous ; the 
former teem with fossil fish, and the latter with the exuviae of mollus- 
cous and radiate animals ; but, according to our fossil registers, Scot- 
land does not yield the shells, corals, or sponges so abundant in De- 
vonshire ; nor are the ichthyolites of the former found in the latter area : 
they have no organic remains in common. 
It will doubtless be remembered, however, that in his ' Palseozoic Fossils 
of Cornwall, Devon, and West Somerset,' Professor Phillips has figured 
and described as a scale of EoIoptycMus, a fossil found in the slates of 
Meadfoot, near Torquay, in South Devon.f It would seem that this iden- 
tification has not been considered perfectly reliable, since the fossil has 
not found a place in subsequent works on the Devonshire beds, or in Pro- 
fessor Morris's 'Catalogue of British Fossils.' 
This dissimilarity of the organisms of two not very widely separated, 
and, as has been supposed, contemporary sets of deposits, is, to say the 
least, very remarkable. The mineral and mechanical characters of the Old 
Ked rocks may sufficiently explain the absence, in them, of mollusks, and 
other dwellers at the sea-bottom ; but there seems no satisfactory mode of 
accounting for the non-appearance of fishes in the slates and limestones of 
Devon and Cornwall. Various solutions of the problem have been at- 
tempted. We are asked by one to suppose that some geographical diffi- 
culty or barrier separated the two areas and prevented the migration and 
mingling of their inhabitants; whilst another suggests that the Old Eed 
fish were probably at home in fresh water only, and ought not to be looked 
for in beds so decidedly marine as those of Devon and Cornwall. 
The interesting and important discovery, by Sir K. T. Murchison, of the 
intermixture, in the same Devonian bed in Eussia, of the fish of the Upper 
and Middle Old Eed of Scotland with the shells of Devonshire, J leaves 
the difficulty untouched ; nor does it appear that the synchronism of tlie 
representative beds in Britain necessarily flows from it. It proves, of 
course, that the fish and shells lived at one and the same time in Eussian, 
not that they did so in British, waters. We may have an example, 
here, of the distinction between geological conttnijporaneitij and synchrony , 
so ably pointed out, on a recent occasion, by Professor Huxley.§ It is 
possible, for instance, that the fish commenced existence before the shells ; 
that they appeared in Scotland long before their descent upon Eussia ; that 
slowly changing conditions compelled them tardily to abandon their ear- 
lier home for a more congenial one ; and that, on their arrival, they found 
there the invertebrate tribes which subsequently migrated to where the 
foundations of the future Devon and Cornwall were being laid. 
Be this as it may, some geologists, recognizing the synchronism of the 
* 'Manual of Geology,' 2nd edit. (1862), p. 492. 
t Pal. Fos&ils, pi. 57, fig. 25G, p. 133. 
+ ' Siluria,' 3rd edit., p." 382. 
§ Anniversary Address, Qiiait. Journ. Geol. Soc, vol. xvii. part 2. 
VOL. V. 3 N 
