292 ORIGIN OF LIFE IN AMERICA 



Although it is a primitive form, he prefers to put its immigra- 

 tion in the Tertiary rather than in the Cretaceous. The history 

 and development of the Central American and West Indian 

 region he imagines to have been as follows : " Central America, 

 the West Indies and the northern margin of South America, 

 formed in the Mesozoic Period (certainly during the Jurassic 

 and Cretaceous) a continental mass (Antillean Continent), 

 which was bounded by sea to the north and south (Fig. 15). 

 This continent broke up at the end of the Cretaceous, 

 the chief factor in its destruction being the formation 

 of the Caribbean Sea. The northern remnant of this 

 continent, consisting of the Greater Antilles and parts 

 of the present Central America, probably remained a unit 

 up to the Eocene." At the end of the Eocene, he 

 continues, and during the Oligocene and Miocene Periods, 

 the connection between the Greater Antilles and the main- 

 land was severed, being subsequently re-established toward 

 the end of the Tertiary Era (Fig. 20) and again destroyed in 

 recent times. 



My own views are in some respects similar to those of Dr. 

 Ortmann, yet they differ in a few important points. If we 

 begin, say with later Cretaceous times, when a wide marine 

 channel still separated eastern from "western North America, 

 northern South America was submerged, and could not have 

 formed part of the supposed Antillean Continent. Towards 

 the end of the Cretaceous Period, all the Antilles, except the 

 Bahamas, were entirely covered by the sea, according to Pro- 

 fessor Schuchert's paleogeographic maps (Map 95). Yet 

 although the peninsula of Yucatan was then submerged, no 

 deposits of this age are known from Guatemala or Honduras, 

 nor have any Mesozoic or Tertiary beds been discovered in 

 these countries. The North American relationship of the 

 relict fauna inhabiting these countries indicates that they 

 were connected by land with western Mexico. I shall also 

 show later on that this region was united by land with western 

 South America before the Isthmus of Panama came into exis- 

 tence. Possibly the Greater Antilles were not so completely 

 covered by the sea as is assumed. They may have been repre- 

 sented by small islands, and these would have possessed frag- 

 ments of an ancient fauna and flora. Cuba, at any rate, 



