32O PATAGONIAN EXPEDITIONS I PALAEONTOLOGY. 



excepted. Among the contemporaneous deposits in South America, only 

 the Navidad fauna of Chili is related to the Patagonian, and, indeed, in 

 such a degree that we are able to draw valuable conclusions from the 

 comparison with it. 



If we come to compare the Patagonian deposits with other American 

 deposits, the close affinity disappears. In this respect one of the most 

 important points is the dissimilarity of the Miocene fauna of northern 

 Peru (Payta and Tumbez), as described by Grzybowski (1899). This 

 fauna possesses only a few features in common with the Navidad fauna, 

 but hardly any with the Patagonian, and the most important is the pres- 

 ence of a species of Struthiolaria in these beds. For the rest, this fauna 

 (called Ecuadorian province by Grzybowski) shows close affinities to the 

 Caribbean province, /'. e., the Miocene deposits of the West Indies, and 

 even in some respects to the European Miocene. 1 



We have seen above that it was possible to compare our Patagonian 

 material to some extent with Miocene faunas of Europe and North America, 

 and the latter is in a certain degree a dependency or offshoot of the West 

 Indian fauna, but these relations are only very general, consisting in a 

 more or less close affinity of species, but hardly in identity. (The fact 

 that we did not find a larger number of relations to the West Indies is 

 probably due to the chiefly Oligocene, not Miocene, age of the latter beds, 

 according to Ball.) Thus we have on the one hand a close relation of 

 the Patagonian beds to the Chilian, which extends to an identity of a num- 

 ber of species, while, on the other hand, with the Caribbean and European 

 provinces only remote relations can be established. The deposits of 

 northern Peru are closely connected with the Caribbean province, although 

 a few closer relations with the Chilian beds are recognizable. 



For the explanation of these facts we have a theory propounded by v. 

 Ihering, which we may conveniently call his Archiplata-Archhelenis-theory 

 (v. Ihering, 1891, pp. 434, 437, and especially : 1893 ; here on p. 9 a list 

 of other publications by the same author referring to the same subject ; 

 and 1894 p. 404 ff.). 



Von Ihering maintains that South America is not a genetic unit, but 

 consists of two parts, which became united subsequently : a southern part 



'According to Ball (1898 b and in : Science, Novemb. 23, 1900, p. 808) the so-called Miocene 

 of the West Indies is really Oligocene, and this would possibly affect slightly Grzybowski's deter- 

 mination of the age of the Peruvian beds. 



