wok Reviews—Ooal Basin of Central France. 
confirmed by Fayol. The most important contention of Fayol was 
that the coal-seams were formed, not in situ, but by transport; and to 
study this question Mr. Stevenson paid a special visit to examine the 
enormous excavations that have been made in mining the coal by 
stripping. 
The Lower Coal-measures are formed almost wholly of rather coarse 
materials, with some unimportant lenticles of anthracite; the Middle 
Coal-measures consist chiefly of fine materials, and include the great 
coal-beds—mainly a single bed, the Grande Couche, 30 to 60 feet 
thick, but divided into two or more seams in a westerly direction ; 
the Upper Coal-measures comprise more or less coarse detritus, and 
practically contain no coal. 
The strata have a dip of about 30°, and this has been supposed to 
be the original slope of the beds. Fayol conceived that the strata 
were deposited in accordance with their specific gravity, the plant 
debris forming the beds of coal. Mr. Stevenson remarks that when 
one considers the enormous mass of the Grande Couche, not less than 
30,000,000 cubic metres, it is difficult to realize that it could have 
been formed from such vegetable matter as could have been washed in 
from an area of about 26 square miles; and he maintains that the 
form and variations of the Grande Couche leave little room for doubt 
that the bed represents plants which grew where the coal now is. 
The marsh-vegetation consisted of Cordaites trees, with a dense 
growth of ferns, lepidodendra, and other plants; and the sandy 
clay underlying the Grande Couche, crowded with vegetable remains, 
is clayey enough to have prevented downward drainage. 
Evidence is brought forward to show that the strata were exposed 
to tremendous pressure after consolidation. Occasionally the coal 
itself is crushed into small lenticles, which have been rubbed and 
polished. . The author concludes that a differential subsidence, com- 
bined with: the effect of compression and carbonization, would account 
for the high dips, which have been regarded as original. 
Mr. Stevenson promises to publish a monograph on the formation of 
coal-beds. In the present communication he has not considered that 
the quiet, undisturbed condition of the organic remains, both plants 
and animals, so abundant in the coal-shales of Commentry, offered the 
best and most complete refutation of M. Henri Fayol’s theory of the 
transportation and redeposition of the materials of these coal-beds in 
their present resting-place. 
A reference to the great work by M. Chas. Brongniart on the 
wonderful insect fauna of Commentry would show how abundant and 
well preserved are the remains of these delicate and beautiful winged 
organisms.! Whilst in Europe and North America there have been 
described about 120 examples, at Commentry alone, since 1878, 
1300 have been met with, of which the greater part is admirably 
preserved.’ 
After sixteen years of continuous labour, mostly devoted to the 
insect fauna of Commentry, M. Chas. Brongniart brought out his great 
work Histowre des Insectes Fossiles des temps primaires (Ste. Etienne, 
1 See Grou. Mac., 1879, pp. 97-102, Protophasma Dumasii, Ch. Br. 
2 Tbid., 1885, pp. 481-91, Pl. XII, Woodwardia, Caloneura, Corydaloides, ete. 
