DISTRIBUTION 343 
scarce throughout the Cambrian, but in the Ordovician, species and indi- 
viduals abound. 
In the Lower Cambrian (Olenellus beds), thirteen genera of Brachiopods 
are represented, occurring both in North America and in Europe. A marked 
increase is apparent toward the close of the Cambrian, and in the Ordo- 
vician and Silurian, where the climax of their diversity is reached, upwards 
of 2600 species are known. ‘These are distributed chiefly in North America 
and in Europe (Great Britain, Scandinavia, Bohemia, Russia, and Portugal) ; 
but numerous forms are also found in South America, Australia, China, and 
Eastern Siberia. 
In the Devonian Brachiopods are scarcely less plentiful than in the 
Silurian, although a considerable number of genera, especially those belong- 
ing to the Atremata and Neotremata, have now disappeared. The most noted 
European localities where Brachiopods abound are the Eifel, Rhineland, West- 
phalia, the Hartz, Belgium, Devonshire, Boulogne sur Mer, Cabrieres in the 
Cevennes, the Asturias, and the Ural. Canada and the Middle Western 
States of North America also yield great quantities of Brachiopods. 
The Carboniferous of North America and its equivalent horizons in 
Europe and Eastern Asia, together with the so-called Permo-Carboniferous 
of the Salt Range of India and Armenia, are very rich in Brachiopod remains, 
especially those belonging to the Productidae, Strophomenidae, Spiriferidae, and 
Rhynchonellidae. 
In the European Permian, the number of species of Brachiopods is reduced 
to about thirty, but in the Salt Range of India greater numbers occur. In 
the Alpine Trias, the Yerebratulidae, Rhynchonellidae, and Koninckinidae attain 
an enormous development. 
The Jurassic and Cretaceous Brachiopods belong almost exclusively to the 
Terebratulidae, Rhynchonellidae, and the Thecidiidae ; the first two families in 
particular being represented by an astonishing number of species. The 
Spiriferacea become extinct in the Lias. 
With the beginning of the Cenozoic era, Brachiopods are no longer a con- 
spicuous group of fossils. The species occurring in the Tertiary are almost 
without exception generically identical with those now living, and scarcely 
exceed them in number. On this account they are devoid of practical 
interest or importance to the geologist. 
[The credit for having revised and practically rewritten the translation of the entire 
Brachiopod chapter belongs to Mr. Charles Schuchert, of the United States National Museum. 
The classification adopted has been taken from his Synopsis of American Fossil Brachiopoda, 
now in press. —TRANS. ] 
