THE GEOLOGIST. 
sentiug the comb-like form of very minute fish jaws, he has called astaco- 
derma. A remarkable form, figured in a diagram exhibited by the author, 
was surrounded by serrated edges, and by one or two ridges in the middle, 
looking in the enlarged form as much like a rat-trap as anything he could 
compare them to, had never before been observed. It is interesting to 
notice that hitherto these curious bodies have only been found in the Lud- 
low bone-bed and its foreign equivalents, but here we have them in the 
carboniferous limestone. They are associated with numerous minute 
spine-like bodies, which appear to have a structure allied to that of fishes. 
Tiiere are teeth of small fishes, and univalves of different species. From 
these facts it appears to the author clear that all the carboniferous lime- 
stone veins, as far as he had been able to examine them, have been with- 
in reach of the ocean, at periods which would be indicated by their organic 
contents, obtaining their materials at one time from the denudation of 
older deposits, at others from the precipitation into them of much younger 
ones. The latter he stated to be the case with those of the Mendip and 
South Wales, whilst in Yorkshire the presence of Silurian conodonts 
would appear to imply the former. 
He had stated that identical organisms occur at certain depths at Alston 
Moor and Weardale, placing them probably on the same horizon. It 
might be a difficult matter for investigation, but he believed it possible, 
by a consideration of this question, that certain horizons in mines might 
be established, not so clearly, of course, as in stratified deposits, but such 
as might enable a mine-manager to know the position of veins relatively 
with mines in other neighbouring districts, and thus know whether he 
might, and at what distances, be passing into barren or pa3nng ground. 
Further, he believed these investigations would assist to establish the fact 
that minerals are due, not to plutonic, but to the very opposite agency. 
The Organic Eemains of the jS'oeth Staffoedshire Coalfield. 
— Mr. Mullins read a report of a committee on the distribution of the or- 
ganic remains of the North Staffordshire coalfield. The report was a 
long and detailed description, and appended to it there were lists of fossils 
collected from sixty-eight distinct beds of coals and ironstones, or, inclu- 
ding subordinate beds, upwards of a hundred. The total number of species 
was stated at from seventy-five to eighty, and of about thirty-five genera. 
In the majority of beds, both of coal and ironstone, the upper surface con- 
tains a substance resembling a bone, and the scales, teeth, and other parts 
of fish, which have, beyond all doubt, been subjected to the action of water. 
This line is often extended into the body of the ironstone, but in no instance 
has it been known to penetrate the body of the coal. 
On the Chronological Value of the Lower Triassic Rocks of 
Devonshire. By Mr. Wm. Pengelly, F.E.S. — The author stated that the 
red rocks of Devonshire were eminently detrital, consisting of conglome- 
rates, sandstones, and marls, and belong to the Bunter or Lower Trias. 
They occupy the whole of the country east of a line from Torbay to Por- 
lock, in West Somerset. The general dip is about \o\ degrees in the di- 
rection N. and 44^ degrees E. (true), so that, judging from this horizontal 
extension in this direction, their volume must be enormous. Having 
dwelt at some length on the proposition that the rate of sedimentation 
must be, on the whole, limited by that of the requisite previous denuda- 
tion, he proceeded to show that the amount of deposited matter is not ne- 
cessarily the measure of the denudation which has taken place, or of the 
time expended on it. Amongst other facts in this part of his paper, he 
noticed the occurrence of pebbles of Triassic sandstone in the Triassic con- 
glomerate, of denudational inequalities in the superior surfaces of beds at 
