Over a South Atlantic Continent 45 1 



primitive or oldest or incipient axis of the Andean Cordil- 

 lera; and in part owing to earth-crumpling in part to activity 

 of a row of volcanoes was considerably elevated along its 

 central line. This central line represented the incipient 

 ridge of the Andes, and was largely separated at times along 

 its length by water from the very persistent Guiana-Bra- 

 zilian landmass that by various authors has been called 

 Archenchelis. But in the Bolivian region — possibly at other 

 points also — eastward connections were probably formed 

 with the Archenchelis mass, if we may judge from all we 

 have learned of the plant and animal records. Along this 

 elevated and wide expanse, plants and animals of northern 

 origin and affinity undoubtedly migrated southward from 

 Central America, Mexico and even the States; while rivers 

 and lakes, that were quite distinct from, and differently 

 disposed from those now occupying the region, aided in the 

 migrational movements. 



Now the nearest allies to the Galaxidae and Aplochi- 

 tonidae are the Salmonidae on the one hand, and the Eso- 

 cidae on the other, both however inhabitants of the fresh- 

 waters of the Northern Hemisphere. Derivative forms 

 from these two evolving groups, may well have migrated 

 down along with the numerous genera of plants and ani- 

 mals that we can trace to have pursued this passageway. 

 By late Cretaceous times then, these along with primitive 

 polyprotodont marsupials from the north, reached the high- 

 er ground of Western Patagonia, of Magellan, and the 

 Falklands. Thence they evidently spread eastward along 

 the southern continent, while as yet central and eastern 

 Patagonia, as well as a large part of Argentina, were sub- 

 merged under a Cretaceous sea. 



Then in Tertiary times and onward at intervals till 

 late Miocene days tremendous earth-shrinkage, crumpling, 

 and folding, accompanied by equally pronounced faultings 

 evidently took place mainly in longitudinal direction. The 

 main faulting must have been along or not far from the S. 

 American Pacific coast, and resulted seemingly in a great 

 downthrow of land for hundreds or thousands of fathoms 

 below the Pacific. This left the abrupt and broken strata 

 as the Chilean-Patagonlan coast line. The main upfolding 



