CHAPTER XIV.

GEOGRAPHICAL DISTRIBUTION OF FISHES.

Zoogeography.--General Laws of Distribution.--Species Absent through Barriers.--Species Absent through Failure to Maintain Foothold.--Species Changed through Natural Selection.--Extinction of Species.--Barriers Checking Movements of Marine Species.--Temperature the Central Fact in Distribution.--Agency of Ocean Currents.--Centers of Distribution.--Distribution of Marine Fishes.--Pelagic Fishes.--Bassalian Fishes.--Littoral Fishes.--Distribution of Littoral Fishes by Coast Lines.--Minor Faunal Areas.--Equatorial Fishes most Specialized.--Realms of Distribution of Fresh-water Fishes.--Northern Zone.--Equatorial Zone.--Southern Zone.--Origin of the New Zealand Fauna. 237