VON Jhering. — On the Ancient Connections of N.Z. 437 



late subsidence of the Chilean coast points hkewise the s^reat 

 similarity of the flora and fauna of Chiloe with those of Chile. 

 The Unios, for instance, from Chiloe are identical with those 

 from Chile, and perhaps also with those from New Zealand. 



The opinion of Ochsenius is shared by many renowned 

 geologists, but disputed by others. The facts we have men- 

 tioned may well be in accordance with it, inasmuch as our 

 zoogeographical reflections lead to the conclusion that with 

 the beginning of the Tertiary era, or soon afterwards, an up- 

 heaval, inconsiderable perhaps, must have been going on in 

 the district of the present Andes, which explains why the 

 successively-arriving immigrants of the fresh water could not 

 pass over this barrier. On the other hand, this low central 

 mountain-chain offered a way to the placental mammals of 

 the Argentine Tertiary by which they could accomplish their 

 entrance, probably in the Oligocene, certainly not later than 

 early in the Miocene. 



if we inquire after the aspect of the orographical conditions 

 in early Tertiary times, there are, I think, sufficient facts to 

 give a"^ satisfactory answer. The valley of the Amazon was 

 covered by the sea. Deposits of the Cretaceous sea, in some 

 parts perhaps rather belonging to the Eocene, cover large areas 

 south of the Amazon, eastwards in Para, Paranahyba, Sergipe, 

 &c., as far as Bahia, and westwards in Peru and Bolivia. At 

 the end of the Cretaceous period, and during the Eocene, 

 South America was broken through from ocean to ocean by 

 the sea in the direction of the Amazon. In all probability the 

 upheaval of the Andes had begun already in the Eocene period, 

 and soon afterwards the Pebas strata must have been deposited 

 in brackish water on the foot of the still but little elevated 

 chain of the Andes. According to Boettger the Pebas deposits 

 are of Oligocene age. It is to be supposed that during the 

 Oligocene period a land-communication was existent in the 

 district of the present Andes, between the high land of Guyana 

 and Venezuela (Archiguyana) and Archiplata, by way of 

 which the old fauna of placental mammals would arrive in 

 /Argentina. 



The mammal fauna has its nearest allies in that of the 

 Europea)! Oligocene, which was probably represented in Africa 

 by more or less similar forms. It is true that the supposed 

 Ano'plotlieria of Argentina have been recognised as belonging 

 to another genus (Protcrotherium), but they are, together 

 with the numerous Eodentia, more nearly allied to the Euro- 

 pean Oligocene fauna than to any other. Schlosser has pointed 

 out that the Theridomydcs of the European Oligocene passed 

 over to South America as Ciiinchillida, Echimyidoi, and 

 CaviadcB. Of these Eodentia scanty remains are found on the 

 Antilles and in Africa, and none, either recent or fossil, in 



