cx PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 
im which the Upper Silurian rocks occupy the central portion. Sir 
Roderick Murchison, while pointing out that geologists should refer 
to the great divisions of Upper and Lower Silurian rocks, when com- 
paring distant countries with each other, and not to the mimor sub- 
divisions he adopted in Great Britain, at the same time remarks, 
that however the minor divisions may differ from each other, similar 
types of organic life frequently occur in distant lands when similar 
mineral conditions are repeated. The lowest fossiliferous schists of 
Ginetz and Skrey are said to remind the geologist of the Llandeilo 
flags and schists of England and the alum shales of Sweden, by the 
development of large trilobites, and the genus Battus, which together 
with Orthide and Cystidee mark these deposits. 'The Bohemian 
quartz rocks reminded Sir Roderick of the Caradoc sandstones of 
the British types, with their abundant Trinuclei. The upper divi- 
sion is stated strikingly to resemble the British division of the same 
age, in being like it eminently characterized by a multitude of cham- 
bered shells, some of the characteristic species of which are most 
abundant in the shale between the Ludlow and Wenlock rocks in 
England. The middle group of the upper division of Prague con- 
tains large Pentameri, one of which cannot be distmguished in ex- 
ternal form from P. Knightw, and in Bohemia, as in England, it is 
associated with Terebratula Wilsont. In the same communication 
(a letter to M. Leonhard), Sir Roderick stated that certain rocks 
of the country round Olmutz should be referred to the Devonian 
series, the fossils discovered in them bearing out this inference. 
As connected with the progress of geology, we must not omit to 
mention a lecture of Mr. Lyell, delivered during the past year before 
the Royal Institution, at one of those Friday-evening meetings at 
which so much that is important in various branches of science is 
first given to the public. He referred to the volcanic district of 
Auvergne as one of peculiar interest, since it does not appear to have 
been submerged beneath the sea durimg a period in which its geolo- 
gical and geographical structure, and the animals and plants by 
which it has been inhabited, have undergone a great succession of 
changes. Mr. Lyell thus brings before us terrestrial changes, so to 
speak, which should be equally taken into account when we consider 
the mode in which, on the great scale, rock-accumulations, as well ig- 
neous as aqueous, have been effected in all geological times since land 
rose above sea, affording by its abrasion the detritus among which 
the remains of animals existing at the time became entombed. It is 
highly useful to regard such terrestrial changes with reference to 
geological times, when the regions in which they took place may 
have been depressed beneath the sea and became buried beneath 
accumulations heaped upon them by the agency of water. Mr. 
Lyell dwelt much upon the antiquity to be ascribed to the Puy de 
Tartaret, a type of one of the most modern cones of eruption im 
Central France. After entermg upon much interesting detail, he 
proceeds to show that a lava-current from this crater flowed over a 
bone-deposit, containmg osseous remains referable to the genera 
Equus, Sus, Tarandus, Cervus, Canis, Felis, Martes, Putorius, Sorex, 
