I833-J THE GREAT DROUGHT. 9$ 



terrestrial inhabitants than they now are. The more I reflect on this 

 case, the more interesting it appears: I know of no other instance 

 where we can almost mark the period and manner of the splitting up 

 of one great region into two well-characterized zoological provinces. 

 The geologist, who is fully impressed with the vast oscillations of level 

 which have affected the earth's crust within late periods, will not fear 

 to speculate on the recent elevation of the Mexican platform, or, more 

 probably, on the recent submergence of land in the West Indian 

 Archipelago, as the cause of the present zoological separation of North 

 and South America. The South American character of the West Indian 

 mammals* seems to indicate that this archipelago was formerly united 

 to the southern continent, and that it has subsequently been an area of 

 subsidence. 



When America, and especially North America, possessed its elephants, 

 mastodons, horse, and hollow-horned ruminants, it was much more 

 closely related in its zoological characters to the temperate parts of 

 Europe and Asia than it now is. As the remains of these genera are 

 found on both sides of Behring's Straits f and on the plains of Siberia, 

 we are led to look to the north-western side of North America as the 

 former point of communication between the Old and so-called New 

 World. And as so many species, both living and extinct, of these same 

 genera inhabit and have inhabited, the One World, it seems most probable 

 that the North American elephants, mastodons, horse, and hollow-horned 

 ruminants migrated, on land since submerged near Behring's Straits, 

 from Siberia into North America, and thence, on land since submerged 

 in the W r est Indies, into South America, where for a time they mingled 

 with the forms characteristic of that southern continent, and have since 

 become extinct. 



While travelling through the country, I received several vivid de- 

 scriptions of the effects of a late great drought ; and the account of this 

 may throw some light on the cases where vast numbers of animals of 

 all kinds have been embedded together. The period included between 

 the years 1827 and 1830 is called the " gran seco," or the great drought. 

 During this time so little rain fell, that the vegetation, even to the 

 thistles, failed; the brooks were dried up, and the whole country 

 assumed the appearance of a dusty high road. This was especially 

 the case in the northern part of the province of Buenos Ayres and the 

 southern part of St. F6. Very great numbers of birds, wild animals, 

 cattle, and horses perished from the want of food and water. A man 



* See Dr. Richardson's Report, p. 157; also L'InsfiM, 1837, p. 253. 

 Cuvier says the kinkajou is found in the larger Antilles, but this is doubtful. 

 M. Gervais states that the Didelphis crancrivora is found there. It is certain 

 that the West Indies possess some mammifers peculiar to themselves. A 

 tooth of a mastodon has been brought from Bahama : Edin. New Phil, 

 Journ. 1826, p. 395. 



f See the admirable Appendix by Dr. Buckland to " Beechy's Voyage J * 

 also the writings of Chain isso in M Ko tie b lie's Voyage." 



