TRANSACTIONS OF THE SECTIONS. 91 
Mr. Elias Hall brought forward and explained a mineral map of 
Derbyshire. 
The principal object of Mr. Hall’s remarks was to prove that there 
were three distinct beds of toadstone, dividing the limestone into four 
beds ; and that, taking the regular continuity of the strata into consi- 
deration, it was improbable that the beds of toadstone could be of vol- 
_ eanic origin. 
The direction of the lead veins Mr. Hall stated to be 25° west of 
the magnetic meridian, varying, however, on the south to a direction 
nearly at right angles to the former. He noticed the occurrence of 
lead actually in the toadstone—a vein passing through it—and ob- 
served that Mr. Mawe, who had contradicted this fact, had visited the 
wrong pit, and therefore missed seeing the phenomenon. 
On the Fishes of the Ludlow Rocks, or Upper Beds of the Silurian 
System. By Mr. Murcuison. 
Mr. Murchison briefly explained, that the various remains of fishes 
which he had collected in the uppermost beds of the Silurian System, 
and immediately below their junction with the old red sandstone, having 
been referred to M. Agassiz, had been formed by him into the follow- 
ing genera: Onchus, Pterygotus, Plectrodus, Sclerodus, Thelodus, and 
Sphagodus. Of these genera (drawings of which were exhibited ), the 
two first mentioned only have been found in the overlying old red 
sandstone, but the species in the Silurian rocks are distinct*. These 
new forms are very remarkable as being the most ancient beings of 
their class which geological researches have brought to light; Mr. 
Murchison never having discovered any trace of fishes in the underly- 
ing formations of the Silurian System. They are associated with 
_ shells, crinoidea, and numerous small coprolites, all of which will be 
figured in Mr. Murchison’s forthcoming work “The Geology of the 
Silurian Region.” Dr. Lloyd, the Rev. T. T. Lewis, and Mr. R. W. 
Evans, were alluded to as having greatly aided the author in collecting 
these remains. 
On the Refrigeration of the Earth. By W. Horxins, F.G.S. 
Mr. Hopkins stated that, though it might be difficult to reconcile to 
the mind the idea that the earth we see and stand on was once a fluid 
mass of igneous matter, and is, in fact, now a great cinder, yet that 
the evidence in favour of such a theory had convinced some of the 
greatest philosophers. The fact, indeed, of the original fluidity of the 
earth is established by its form, since, if fluid, it must, as a body re- 
volving on an axis, have deviated from a globular form, and such is 
* The Pterygotus of the Ludlow Rocks is supposed by M. Agassiz to belong to the 
same genus of fishes as the remarkable form which occurs in the lower beds of the 
old red sandstone of Scotland, and is there called by the workmen “ Seraphim.” 
