Geographical Distribution. 211 



place, or places, on the earth's surface other than 

 that in which they occur ; and hence we must say 

 that one of the objects of special creation if this 

 be the true theory was that of depositing species 

 in only some among the several parts of the earth's 

 surface equally well suited to support them. 



Now, I do not contend that this fact in itself raises 

 any difficulty against the theory of special creation. 

 But I do think that a very serious difficulty is raised 

 when to this fact we add another namely, that on 

 every biological region we encounter species related 

 to other species in genera, and usually also genera 

 related to other genera in families. For if each of 

 all the constituent species of a genus, and even of a 

 family, were separately created, we must hence con- 

 clude that in depositing them there was an unaccount- 

 able design manifested to make areas of distribution 

 correspond to the natural affinities of their inhabi- 

 tants. For example, the humming-birds are geogra- 

 phically restricted to America, and number 120 

 genera, comprising over 400 species. Hence, if this 

 betokens 400 separate acts of creation, it cannot 

 possibly have been due to chance that they were 

 all performed on the same continent : it must have 

 been design which led to every species of this large 

 family of birds having been deposited in one geogra- 

 phical area. Or, to take a case where only the 

 species of a single genus are concerned. The rats 

 and mice proper constitute a genus which comprises 

 altogether more than 100 species, and they are all 

 exclusively restricted to the Old World. In the 

 New World they are represented by another genus 

 comprising about 70 species, which resemble their 

 P a 



