ORTMANN I TERTIARY INVERTEBRATES. 323 



entirely different from the extratropical fauna to the north of the tropics. 

 This fauna, of course, developed as soon as the climatic differentiation of 

 the South Pole offered the necessary conditions, and we may say that for 

 a large part of this fauna the shores of the supposed Antarctic continent 

 formed the center of origin. Since Miocene Patagonia was apparently a 

 part of this center, it is only natural that we should find here indications 

 of this Antarctic fauna. 



Some elements of the latter in the Patagonian beds are no doubt the 

 ancestors of corresponding forms still living in these regions, and a few 

 of them have not changed at all, so that they must be regarded as iden- 

 tical species, for instance (compare p. 289): Aspidostoma giganteum, Tere- 

 bratella dorsata, Mytilus magellanicus, Infundibulum corrugatum, Infun- 

 dibulum clypeohim, Verruca Icevigata, Balanus psittacus. One species, 

 Mytilus chorus, is no longer found in southern Patagonia, but has retreated 

 a little northward, to Chili. Other species are no longer found in South 

 America: Cellaria fistiilosa (otherwise almost cosmopolitan), Heteropora 

 pelliculata (New Zealand and Japan), Rhynchonella sqtiamosa (Kerguelen 

 Islands), Magellania lenticularis (New Zealand). 



In other cases, the fossil and living species are to be regarded as dif- 

 ferent, but they are apparently genetically connected. This is the case in 

 the following genera (see v. Ihering, 1897 b, p. 532): Valuta, Trophon, 

 Turritella, Natica, Vemis, Meretrix, Dosinia, Pecten, to which we may 

 add Bouchardia. This is especially remarkable in the genus Valuta, 

 where three chief types of living Patagonian Volute, V. ancilla, magel- 

 lanica, and brasiliana, have their prototypes in the following species : V. 

 dorbignyana, dotneykoana and ameghinoi. 



While all these forms are characteristic of the American part of the 

 Antarctica, some of them, for instance the Volute, reappear in similar 

 types in Australia and New Zealand. The same is true of Siphonalia 

 domeykoana, which does not seem to exist at present in South America, 

 but it is still represented in the recent seas of New Zealand in S. dila- 

 tata, and analogous are the cases of Struthiolaria, Malletia, Sigapatella. 

 Struthiolaria is found fossil in South America (Oligocene of Patagonia, 

 Miocene of Patagonia, Chili, and northern Peru) and in New Zealand 

 (Miocene upward) and still lives in New Zealand waters. Malletia is 

 known fossil from the Miocene of Patagonia, Chili, and New Zealand, and 

 living from Chili and New Zealand. Sigapatella is found in the Miocene 



