THE PLIOCENE PERIOD. a2 
Arvernensis), which is hitherto the only Mastodon found in 
Britain. 
According to the most recent views of high authorities, 
certain deposits—such as the so-called “ Bridlington Crag” of 
Yorkshire, and the ‘‘ Chillesford beds ” of Suffolk—are to be 
also included in the Newer Pliocene, upon the ground that 
they contain a small proportion of extinct shells. Our know- 
ledge, however, of the existing Molluscan fauna, is still so far 
incomplete, that it may reasonably be doubted if these sup- 
posed extinct forms have actually made their final disappear- 
ance, whilst the strata in question have a strong natural con- 
nection with the “ Glacial deposits,” as shown by the number 
of Arctic Mollusca which they contain. Here, therefore, these 
beds will be included in the Post-Phocene series, in spite of 
the fact that some of their species of shells are not known to 
exist at the present day. 
The following are the more important Pliocene deposits 
which have been hitherto recognised out of Britain:— 
t. In the neighbourhood of Antwerp occur certain “ crags,” 
which are the equivalent of the White and Red Crag in part. 
The lowest of these contains less than 50 per cent, and the 
highest 60 per cent, of existing species of shells, the remainder 
being extinct. 
2. Bordering the chain of the Apennines, in Italy, on both 
sides is a series of low hills made up of Tertiary strata, which 
are known as the Sub-Apennine beds. Part of these is of 
Miocene age, part is Older Pliocene, and a portion is Newer 
Pliocene. The Older Phocene portion of the Sub-Apennines 
consists of blue or brown marls, which sometimes attain a 
thickness of 2000 feet. 
3. In the valley of the Arno, above Florence, are both 
Older and Newer Pliocene strata. The former consist of blue 
clays and lignites, with an abundance of plants. The latter 
consist of sands and conglomerates, with remains of large Car- 
nivorous Mammals, Mastodon, Elephant, Rhinoceros, Hippo- 
potamus, &c. 
4. In Sicily, Newer Pliocene strata are probably more largely 
developed than anywhere else in the world, rising sometimes 
to a height of 3000 feet above the sea. ‘The series consists 
of clays, marls, sands, and conglomerates, capped by a com- 
pact limestone, which attains a thickness of from 700 to 800 
feet. The fossils of these beds belong almost entirely to living 
species, one of the commonest being the Great Scallop of the 
Mediterranean (Pecten Jacobeus). 
5. Occupying an extensive area round the Caspian, Aral, 
