376 COMPARATIVE ZOOLOGY. 
The New-world fauna is old-fashioned, and inferior in 
rank and size, compared with that of the eastern con¬ 
tinents. 
As a rule, the more isolated a region the greater the 
variety. Oceanic islands have comparatively few species, 
but a large proportion of endemic or peculiar forms. Ba- 
trachians are absent, and there are no indigenous terrestrial 
Mammals. The productions are related to those of the 
nearest continent. When an island, as Britain, is sepa¬ 
rated from the mainland by a ohallow channel, the mam¬ 
malian life is the same on both sides. 
Protozoans, Coelenterates, and Echinoderms are limited 
to the waters, and nearly all are marine. Sponges are 
mostly obtained from the Grecian Archipelago and Baha¬ 
mas, but species not commercially valuable abound in all 
seas. Coral-reefs abound throughout the Indian Ocean 
and Polynesia, east coast of Africa, Bed Sea, and Persian 
Gulf, West Indies, and around Elorida; and Corals which 
do not form reefs are much more widely distributed, be¬ 
ing found as far north as Long Island Sound and Eng¬ 
land. Crinoids have been found, usually in deep sea, in 
very widely separated parts of the world—off the coast of 
Norway, Scotland, and Portugal, and near the East and 
West Indies. The other Echinoderms abound in almost 
every sea: the Star-fishes chiefly along the shore, the Sea- 
urchins in the Laminarian zone, and the Sea-slugs around 
coral-reefs. Worms are found in all parts of the world, 
in sea, fresh water, and earth. They are most plentiful 
in the muddy or sandy bottoms of shallow seas. Living 
Brachiopods, though few in number, occur in tropical, 
temperate, and arctic seas, and from the shore to great 
depths. Polyzoa have both salt and fresh water forms, 
and Annelids include land forms, as the Earth-worm and 
some Leeches. 
Mollusks have a world-wide distribution over land and 
