6 Merriam Geographic Distribution of Life. 



pines, elk, moose, reindeer, sables, fishers, wolverines, lemmings, 

 musk oxen, and polar bears. 



The trogons, saw-bills, parrots, cotingas and other birds of 

 tropical America give place in turn to the cardinals, blue gros- 

 beaks, mocking birds, tufted tits, and gnatcatchers of the South- 

 ern States ; the chewink, indigo bird, tanager, blucl >ird, and robin 

 of the Middle and Northern States; the Canada jays, crossbills, 

 white-throated sparrows, and hawk owls of the northern conifer- 

 ous forests, and the ptarmigans, snowy owls, and snowflakes of 

 the Arctic circle. 



HISTORICAL SYNOPSIS OF FAUNAL AND FLORAL DIVISIONS 

 PROPOSED FOR NORTH AMERICA. 



The recognition of the above-mentioned facts early led to 

 attempts to divide the surface of the land into faunal and floral 

 regions or zones, and no less than 56 authors have proposed such 

 divisions for North America. Of these, 31 were zoologists and 25 

 botanists. Of the zoologists, 10 aimed to show the distribution 

 of animals in general, 8 of birds, 4 of terrestrial mollusks, 3 of 

 mammals, 1 of reptiles and batrachians, and 4 of insects. Of the 

 botanists, 22 aimed to show the distribution of plants in general 

 and 3 of forest trees. 



Of the writers who attempted to indicate the life areas of 

 the New World prior to 1850, 68 percent were botanists, while 

 during the next twenty years (1850-1870), 65 percent were 

 zoologists. This striking oscillation of the biologic pendulum, 

 first toward botany and then toward zoology, may be attributed 

 in part at least to the influence of two great minds Hum- 

 boldt and Agassiz. Humboldt laid the corner-stone of the 

 philosophic study of plant geography in 1805. Stimulated by 

 his example and writings, botanists led the way and were almost 

 the only occupants of the field until the middle of the present 

 century, when the influence of the elder Agassiz gained the 

 ascendency and the botanists were replaced by zoologists, who 

 have been in the lead ever since. 



The accompanying table shows the various authors referred to, 

 the dates of the earliest publication of their divisions, the branch 

 of biology on which their conclusions were based, and states 

 whether or not their articles were accompanied by maps. 



