But the subject with which Milius especially grapples is the DISTRIBUTION of animals.

He is greatly exercised by the many species found in America and in remote islands of the ocean--species entirely unknown in the other continents--and of course he is especially troubled by the fact that these species existing in those exceedingly remote parts of the earth do not exist in the neighbourhood of Mount Ararat.

He confesses that to explain the distribution of animals is the most difficult part of the problem.

If it be urged that birds could reach America by flying and fishes by swimming, he asks, "What of the beasts which neither fly nor swim ?" Yet even as to the birds he asks, "Is there not an infinite variety of winged creatures who fly so slowly and heavily, and have such a horror of the water, that they would not even dare trust themselves to fly over a wide river ?" As to fishes, he says, "They are very averse to wandering from their native waters," and he shows that there are now reported many species of American and East Indian fishes entirely unknown on the other continents, whose presence, therefore, can not be explained by any theory of natural dispersion.
Of those who suggest that land animals may have been dispersed over the earth by the direct agency of man for his use or pleasure he asks: "Who would like to get different sorts of lions, bears, tigers, and other ferocious and noxious creatures on board ship?
who would trust himself with them?
and who would wish to plant colonies of such creatures in new, desirable lands ?" His conclusion is that plants and animals take their origin in the lands wherein they are found; an opinion which he supports by quoting from the two narrations in Genesis passages which imply generative force in earth and water.
But in the eighteenth century matters had become even worse for the theological view.

To meet the difficulty the eminent Benedictine, Dom Calmet, in his Commentary, expressed the belief that all the species of a genus had originally formed one species, and he dwelt on this view as one which enabled him to explain the possibility of gathering all animals into the ark.