PRINCIPLES OF GEOLOGY -- VOLUME 3

GENERAL RESULTS

DEDUCED PROM A COMPARISON OF THE SPECIES EXAMINED IN COMPILING THE FOREGOING TABLES.

PLIOCENE PERIOD.

Italy, Sicily, the Morea, Perpignan, and the English Crag. The fossils of Perpignan and the Morea are, with the exception of three or four species, the same as those of Italy.

The number of living analogues is 350, which is in the proportion of 49 in 100.

MIOCENE PERIOD.

Bordeaux, Dax, Touraine, Turin, Baden, Vienna, Moravia, Hungary, Cracovia, Volhynia, Podolia, Transylvania, Angers, and Ronca. [2]

The species of Moravia, Hungary, Cracovia, Volhynia, Podolia, and Transylvania, are the same, with a very few exceptions, as those of Vienna and Baden.

The number of living analogues is 176, which is in the proportion of rather less than 18 in 100; the number of fossil analogues, after subtracting those which pass from the Miocene into both the Pliocene and Eocene epochs, is 168, which is very nearly in the same proportion.

The species which pass from the Miocene into the Pliocene period are in number 196, of which 114 are living, and 82 fossil, which is very nearly in the proportion of 20 in 100 of the total number of species of the latter epoch. Thus it is remarkable that there are 18 in 100 living analogues, 18 in 100 of analogous fossil species, and that 20 in 100 of these species pass from the Miocene to the Pliocene epoch.

The 114 living species, and the 82 fossil ones, which are common to the Miocene and Pliocene periods, are distributed, in the last- mentioned epoch, in the following manner: --

The preceding distribution of species will show that Italy is represented in the Miocene period by 181 species, Sicily by 69, and the Crag by 20.

EOCENE PERIOD.

Paris, London, Valognes, Belgium, Castelgomberto, and Pauliac.

A small number of species only have been examined from Belgium, Pauliac, and Castelgomberto, but which agreed, with few exceptions, with species of the Paris basin. So also in regard to Valognes.

The number of fossils of this period identified with living species is 42, which is to 1238 in the proportion of 31 in 100. The number of fossil species which pass from the Eocene into the two other periods is 46. that is to say. in nearly the same proportion as the living analogues. Among the fossil species, four only are common to the three epochs, which are the following: --

1 Dentalium coarctatum.
2 Tornatella inflata.
3 Bulimus terebellatus.
4 Corbula complanata.

The 42 other fossil species, which go no farther than the Miocene epoch, are distributed in the following manner: --

Of the 42 living species, the following 13 are common to the three epochs, --

1 Dentalium entalis,
2 ---------- strangulatum,
3 Fissurella graeca,
4 Bulla lignaria,
5 Rissoa cochlearella,
6 Murex fistulosus,
7 Murex tubifer,
8 Polymorphina gibba,
9 Triloculina oblonga,
10 Lucina divaricata,
11 ---------- gibbosula,
12 Isocardia cor,
13 Nucula margaritacea.

Of the other species, 7 go no farther than the Miocene epoch, and are distributed in the following manner, --

Total number of species in the three periods, --

From the above lists it will appear that there are 17 species which are common to the three epochs. and which may therefore be said to characterise the entire tertiary formations of Europe. Thirteen of them are species still living, while four are only known as fossil. There is not a single species common to the Pliocene and Eocene epochs which is not also found in the Miocene.

GEOGRAPHICAL DISTRIBUTION OF THE LIV1NG SPECIES WHICH HAVE THEIR FOSSIL ANALOGUES.

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Notes:

1.  The statement that there are only 4 species common to Italy and the Crag, may seem inconsistent with the fact that 18 are common to those places and to Sicily; but the reader will understand that there are only 4 species which are common to Italy and the Crag, and which are not also common to some other Pliocene locality. The same remark is applicable to similar statements in the sequel.

2.  Ronca may very probably belong to the Eocene epoch; but in this, as in respect to a few other localities mentioned in the tables, the number of analogues is too small to lead to certain conclusions.

3. 

but from the great number of species common to the two localities there are, in reality, only 594 species, as above mentioned.

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