xviii PHYSIOLOGY AND MORPHOLOGY OF ANIMALS. 

 CHAPTER VI. 



GEOGRAPHICAL DISTRIBUTION OF ORGANISMS. 



Definition of fauna and flora, 471. Illustration of harmonic rela- 

 tions of faunas, botanical temperature regions, 472. Zoological tem- 

 perature regions, completer definition of temperature regions, range of 

 species, genera, etc., 474. Mode of grading of contiguous ranges, 475. 

 Effect of barriers, 475. 



Continental i'aunal regions, species usually distinct, 477. Excep- 

 tions, 478. Subdivisions of continental faunas, 479. Special cases : 

 (1) Australia, 479; (2) Madagascar, 480; (3) Galapagos, 481. River 

 mussels, 481. 



Marine Faunas. — Temperature regions of east coast of United 

 States, 481. Shore faunas, pelagic fauna, abyssal faunas, special cases, 

 482. 



Primary Division of Land Faunas. — Wallace's divisions, 483. 

 Schedule of regions and provinces, subdivisions of the Nearctic, 484. 



Theories of the Origin ef Distribution of Organisms. — Old theory, 

 485. New theory, 487. Examples of explanation by new theory : 

 (1) Alpine species, (2) Australia, 488 ; (3) Africa, 4S9. Islands, kinds 

 of, (4) Madagascar, 490 ; (5) British Isles, (6) California coast islands, 

 491 ; (7) oceanic islands, 492. 



