TRANSACTIONS OF THE SECTIONS. 109 
siliferous group (stage D) discovered in Bohemia by M. EBarrande*. The lowest 
group, characterized in Sweden, N. Wales, the Malvern Hills, and in Bohemia by 
the Paradowides, is wanting both in Spain and in Brittany, an analogy which proves 
the intimate connexion which exists between the palozoic rocks of these two 
countries. 
The upper Silurian rocks appear to be poorly represented in the Sierra Morena. 
In a single spot about twenty miles N.E. of Cordova, M. de Verneuil saw bitumi- 
nous schists with spheroidal calcareous concretions very similar to those which exist 
at St. Sauveur le Vicomte, Feuguerolles and St. Jean sur Erve in Western France, 
and which occur alsoin Bohemia. In this last country M. Barrande has paid much 
attention to such bituminous beds, as they there occur both in the lower and upper 
Silurian rocks, and, though separated by more than 2000 feet of strata, contain the 
same group of fossils. In Spain these concretions contain, as in many other tracts, 
Cardiola interrupta, Orthoceras styloideum, and O. Bohemicumt. 
The Devonian rocks are fully developed in the Sierra Morena north and south of 
Almaden, and it is possible that even the quartzites and schists, in which the cele- 
brated mines of mercury are worked, belong to that period}: the Devonian fossils 
occur generally in sandstones or in very small bands of impure limestone ; the most 
characteristic are Productus subaculeatus, Leptena Dutertrii, Spirifer Verneuili, 
S. Archiaci, S. Bouchardi, Orthis striatula, Terebratula reticularis, T. Orbigniana, 
T. concentrica, Phacops latifrons. 
~The carboniferous deposits of the Sierra Morena are situated towards its southern 
part. They contain generally great masses of limestone, in which occurs the Productus 
semireticulatus, so characteristic of the mountain limestone of England, Belgium, 
Russia as far as the neighbourhood of Archangel, and even of Spitzbergen. Such 
a vast distribution of the same species over areas which at the present day present 
so great a difference of climate, is one of those phenomena which specially deserve 
the attention of philosophers. 
The best coal-fields of the Sierra Morena are those of Belmez and Espiel on the 
Guadiato, and those of Villanueva del Rio, twenty miles N.N.E. of Seville. The 
first is about twenty-seven or twenty-nine miles long; the strata are vertical, and 
some are very rich; but the difficulty of the communication and the total want of 
roads have limited the working to some local uses. The coal tract of Villanueva del 
Rio, situated near the valley of the Guadalquivir, is more valuable. 
If Silurian fossils are as yet known only in the Sierra Morena, it is not so with 
the Devonian fossils. The two sides of the Sierra Cantabrica in Leon and the Astu- 
Trias, present one of the richest developments of the deposits of that age. Thanks to 
the researches of MM. Paillette and Casiano de Prado, many Devonian fossils have 
been discovered; and M. de Verneuil having himself visited the localities, has de- 
scribed or given a list of more than sixty species. Sabero in the kingdom of Leon, 
and Ferrones in the Asturias, ought really, he says, to be places of pilgrimage for 
all palzontologists. These Devonian rocks constitute the axis of the Sierra Canta- 
brica on its southern side, and are covered in the Asturias or on the north by the 
richest coal-field of Spain. In general the carboniferous strata are vertical, as in the 
Sierra Morena; but this disadvantage is lessened by the mountainous relief of the 
country, in some parts of which the beds of coal can be worked 1200 or 1300 feet 
above the level of the streams. There being more than eighty workable beds, the 
depth of the whole system must be very great, and may be estimated at 10,000 or 
12,000 feet. At the base is a thick mass of limestone with Productus: but most of 
the carboniferous mollusca are to be found in bands of limestone alternating with 
the inferior strata of the great coal deposit. Among the fossils worthy of notice, 
are the Fusulina cylindrica, till now found only in Russia and in the United States, 
* See the review of M. Barrande’s labours which follows. 
t The same fossils occur in Catalonia near San Juan de las Abadessas, where they have 
been discovered by M. Amalio Maestre; they have been quoted by Prof. Leymerie near St 
Beat on the north side of the Pyrenees, and exist also in Sardinia. Ἵ 
Ὁ The mercury of Almaden is not in veins, but seems to have impregnated three vertical 
strata of a quartzose sandstone associated to slates rather carbonaceous. The association of 
mercury with carbonaceous rocks is still more remarkable in Asturias, where mines of mer- 
cury are worked in coal-measures. ὁ, 
