422 
SILUKIA. 
[Chap. XVII. 
neighbouring portion of the Mediterranean, we again meet in Sardinia with a 
similar succession of Palaeozoic deposits. Geologists owe this determination 
to the researches of General de la Marmora, so long favourably known to geo- 
graphers for his beautiful topographical map of that island. Judging from cer- 
tain Orthidse and Orthocerata which this author sent to me in the year 1848, 
I had no doubt that Silurian rocks existed in Sardinia, as laid down indeed 
by Collegno in his geological map of Italy. I have since been informed by M. 
Barrande, who has personally inspected the rocks and fossils in the southern 
part of the island, near Flumini Maggiore, that in his opinion both Lower and 
Upper Silurian rocks are there present. 
In addition to the work by General de la Marmora, accompanied by an ela- 
borate map, it has been shown by Professor Meneghini of Pisa that several of 
the fossils collected by the General and his assistant M. Vecchi are well-known 
Silurian forms. Among these may be mentioned Orthis Lusitanica, Sharpe, 0. 
testudinaria and 0. vespertilio, Sow., &c. Other fossils are, on the contrary, 
Upper-Silurian types, such as Orthoceras ibex, 0. gregarium ?, Sow., and several 
others, besides Cardiola and Avicula. 
General de la Marmora informs us that all these Silurian or other rocks *, 
and the metamorphic masses with which they are associated, are distinctly sur- 
mounted by strata containing anthracitic coal, charged with many of the fossil 
Plants which prevail in the old Coal-deposits of other regions. Thus among 
the fossils from Seni and Sculo Professor Meneghini has recognized Pecopteris 
arborescens, P. dentata, P. unita, P. polymorpha, P. hemiteloides, and several 
others, with species of the genera Odontopteris, Neuropteris, Sphenophyllum, 
Annularia, Asterophyllia, Sigillaria, Syringodendron, and an abundance of the 
well-known Calamites Suckowi. 
In fact, the strata in which these Coal-plants occur, and which terminate 
downwards in conglomerates f> rest in completely discordant positions on the 
older rocks, and in this highly altered tract are covered by dolomites of the 
Jurassic age. 
Schists and conglomerates, though not so carbonaceous, but charged with 
many Plants similar to those of Sardinia, have indeed been described by Pro- 
fessors Meneghini and Savi in the older rocks of Tuscany, which at Jano con- 
tain Productus semireticulatus and other Carboniferous fossils. This group of 
rocks is therefore no longer to be vaguely classed as Palaeozoic, but takes 
a definite place, like parts of the Carinthian Alps near Bleiberg, where the same 
animal-remains occur, and thus is proved to be truly of the Carboniferous epoch. 
These facts, which were unknown in 1848, when I last published upon the Alps 
and Apennines %, are most important, and lead us to infer that the traces of the 
coal which are associated with certain Land Plants in parts of the Western 
Alps, are also of the old Carboniferous age ; for the conglomerates and schists 
with which such plants are associated in the Alps are the precise equivalents of 
the ' Verrucano ' and schists of Sardinia and Northern Italy ; and these lie be- 
neath strata of Triassic, Liassic, and Jurassic age. 
It has already been stated that rocks containing Silurian, Devonian, and Car- 
* It is right to state that whilst M. de Verneuil p. 157, and particularly its translation into Italian 
has seen unquestionable Upper-Silurian fossils by Professors P. Savi and Meneghini, entitled 
from Sardinia, which on the part of General de la • Struttura Geologica delle Alpi, degli Apennini e 
Marmora I submitted to him, he is of opinion dei Carpazi,' followed by their ' Consiaerazioni 
that some of the fossils (of which, however, he sulla Geologia della Toscana ' (Florence, 1850), in 
only saw drawings) are of Devonian age. It is which these distinguished Italian geologists an- 
probable, therefore, that the succession will even- nounced the important discovery of the true old 
tually be found to be similar to that of Spain. Carboniferous formation in the hills near Volterra. 
t See my Memoir on the Alps, Apennines, and J Quart. Journ. Geol. Soc. Lond. vol. v. pp. 
Carpathians, Quart. Journ. Geol. Soc. Lond. vol. v. 167, &c. 
