oO Mcrriam — (reogroj)hic Distri/nUion of Life. 



Itutiou of life. He lays greiit stress upon the dissiiuilarity of the 

 launas and Hovas of [)arts of Africa, South America, and Aus- 

 traha Ivinji' in llie same kititude and calls i)arlicular attention to 

 the circumstance that although the climate may he identical 

 over these widely sei)arated areas, the species and higher groups 

 are totally distinct, hecause the regions luive l)een disconnected 

 since early geologic times — as if these facts were not self-evident. 

 On the other hand, in single continental areas where there is no 

 break or barrier of any kind between widely different ftiunal 

 zones, he tries to invent some unnatural reason for the differences 

 observed and is reluctant to admit that even in these cases 

 climate or climatic conditions can constitute the l)arriers to dis- 

 persion that undoubtedly exist. He says of climate : " Probably 

 its action is indirect, and is determined by its influence on vege- 

 tation, and by bringing diverse groups into competition." 



In another place he states: "Hot countries usually differ 

 widelv from cold ones in all their organic forms ; but the differ- 

 ence is by no means constant, nor does it l)ear any proportion to 

 difference of temperature. Between frigid Canada and sub- 

 tropical Florida there are less marked differences in tlu; animal 

 productions than between Florida and Cuba or Yucatan, so 

 much more alike in climate and so much nearer together." He 

 states further : " The eastern United States possess very peculiar 

 and interesting plants and animals, the vegetation becoming 

 more luxuriant as Ave go south l)ut not altering in essential 

 character; so that when we reach the southern extremity of 

 Florida we still lind ourselves in the midst of oaks, sumacs, 

 magnolias, vines, and other characteristic forms of the temperate 

 flora; while the birds, insects, and land-shells are almost iden- 

 tical with those found further north. But if we now cross over 

 the narrow strait, al)out fifty miles wide, which separates Florida 

 from the Bahama Islands, we find ourselves in a totally different 

 country, surrounded by a vegetation which is essentially tro})ical 

 and generally identical with tliat of Cuba. The change is most 

 striking, because there is no ditference of climate, of soil, or 

 apparently of position, to account for it." (Island Life, 1880, 

 p. 5.) 



Let us examine this statement with some care to see if the facts 

 warrant the assertions and conclusions oi' the author. But first 

 let nu' ]»rotest against Wallace's habit of contrasting insular 

 faunas with those ol' contimidus land areas, in his cilnrts to mini- 

 mize the efi'ects <>f climate, in most cases the trrcat maioritv of 



