FUNDAMENTAL RELATIONS OF ANIMALS 45 



have been the case in the circumstance, that representative species, 

 which, as distinct species, must have had from the beginning a differ- 

 ent and distinct geographical range, frequently occupy sections of 

 areas which are simultaneously inhabited by the representatives of 

 other species, which are perfectly identical over the whole area.^^ 

 By way of an example, I would mention the European and the 

 American Widgeon (Anas Penelope and A. americana), or the 

 American and the European Red-headed Ducks [A. ferina and A. 

 erythrocephala), which inhabit respectively the northern parts of the 

 Old and New World in summer and migrate further south in these 

 same continents during winter, while the Mallard (A. Boschas) and 

 the Scaup Duck (A. marila) are as common in North America as 

 in Europe. What do these facts tell? That all these birds originated 

 together somewhere where they no longer occur, to establish them- 

 selves in the end within the limits they now occupy? — or that they 

 originated either in Europe or America, where, it is true, they do 

 not live all together, but at least a part of them? — or that they really 

 originated within the natural boundaries they occupy? I suppose 

 with sensible readers I need only argue the conclusions flowing from 

 the last supposition. If so, the American Widgeon and the American 

 Red-headed Duck originated in America, and the European Widgeon 

 and the European Red-headed Duck in Europe. But what of the 

 Mallard and the Scaup, which are equally common upon the two 

 continents? Did they first appear in Europe, or in America, or simul- 

 taneously upon the two continents? Without entering into further 

 details, as I have only desired to lay clearly a distinct case before 

 my readers from which the character of the argument, which applies 

 to the whole animal kingdom, may be fully understood — I say that 

 the facts lead, step by step, to the inference, that such birds as the 

 Mallard and the Scaup originated simultaneously and separately in 

 Europe and in America and that all animals originated in vast num- 

 bers, indeed, in the average number characteristic of their species, 

 over the whole of their geographical area, whether its surface be 

 continuous or disconnected by sea, lakes, or rivers, or by differences 

 of level above the sea, etc. The details of the geographical distribu- 



^ [See Agassiz, "Prefatory Remarks," in Nott and Gliddon, Indigenous Races of the 

 Earth (Philadelphia, 1857), pp. xiii-xv, and A Journey in Brazil (Boston, 1868), pp. 

 529-532, for elaborations upon the concept of the plural origins of animal forms with 

 particular reference to man.] 



