ANIMAL GEOGRAPHY 



By KARL P. SCHMIDT 

 Chicago 'Natural History Museum 



The comprehensive work on the subject of Animal Geography, published in 

 1853 by Ludwig Schmarda, of the University of Gratz, serves very well as a 

 summary of the state of knowledge in this field in the eighteen-fifties. Die geo- 

 graphische Verhreitung der Thiers devotes 93 pages (with no less than 129 pages 

 of notes and references) to the modality and causality of animal distribution, in 

 which he discusses the influences of heat, light, air, electricity, climate, seasonal 

 cycles, and food, much as the ecological factors in animal distribution are set 

 forth today. In this section it is apparent that the data were in every respect 

 inadequate for a comprehensive review in 1850. Schmarda goes on to discuss 

 the dependence of animals on their medium and substrate, the altitude distribu- 

 tion of both land and marine animals, general ideas about dispersal, and the 

 concepts of faunas and zoological regions. He has taken the step, bold enough 

 for 1853, of giving up the concept of a single center of creation and of dispersal 

 in favor of a number of such centers. He is aware also of the phenomenon of 

 vicariation, of the replacement of one species of animal by an obviously related 

 one in adjacent areas or regions. His twenty-one terrestrial and ten marine regions 

 are rather casually chosen and as casually characterized by some dominant group 

 — the Middle European Realm, for example, is the realm of insectivores and of 

 carabid and staphylinid beetles, IMadagascar the realm of lemurs. The discussion 

 of the terrestrial regions occupies 143 pages, with 258 pages of references, and 

 that of the marine regions 58 pages with 94 pages of notes. A colored Mercator 

 map delimits the 31 realms. 



On the eve of the revolution in zoological thought brought about by Darwin's 

 Origin of Species, the delimitation of the principal faunal regions of the world 

 was the principal preoccupation of zoologists interested in distribution. Thus in 

 1858 P. L. Sclater set forth the principal terrestrial regions as indicated by birds, 

 and in the same year Albert Glinthor did the same for reptiles, with a very fair 

 agreement between the two distinct approaches. 



The appearance of Darwin's Origin of Species in 1859 marked a radical 

 change of direction and an enormous stimulus to botanical and zoological explora- 

 tions and studies in every field. By Darwin's time, the broad patterns of animal 

 distribution shown by the larger and otherwise more conspicuous animal types had 

 been made known, and the existence of these patterns presented increasing diffi- 

 culties to theories of special creation. Thus Darwin's summary of the evidences 

 from animal distribution that favored the evolutionary origin of animal types 

 (whether species, genera, or higher groups) marked the end of the purely descrip- 

 tive era, and the beginning of a period of interpretation and speculation and re- 

 examination of the phenomena in the field of geographic distribution of plant and 

 animal life, as in all other segments of biology. 



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