112 Transactions. 



many respects the fauna is intermediate between that of the Quinquina 

 and that of the Patagonian Miocene, for it has many relationships to both. 

 Nevertheless, he regaids the Patagonian Cretaceous as the equivalent of 

 the Quiriquina ; the differences that are noticed between the faimas are 

 regarded as due to the 1,000 miles of distance which separates the localities. 

 The Patagonian formation is considered by Wilckens to be equivalent to 

 the Navidad, of Miocene age, and the differences between these two series, 

 though somewhat greater than those between the Quiriquina and the 

 Patagonian Cretaceous, are still of the same order of magnitude. 



At first sight, Wilckens says, the Patagonian Upper Cretaceous is ap- 

 parently Tertiary, especially since, with the exception of Baculites, no 

 cephalopods have been found. The bivalve and gastropod fauna, however, 

 contains so many very characteristic Cretaceous genera that no doubt can 

 be entertained that it is of Cretaceous age. Pugnellns and Cinulia are 

 wholly absent from the Tertiary. Trigonia, Pyropsis, and Struthiolariopsis 

 also indicate the Cretaceous. Then come also the very close relationships 

 to the Quiriquina (previously described by him as Senonian). The Pata- 

 gonian Cretaceous contains many elements of the Miocene, and the following 

 eighteen genera are quoted as occurring in both : Schizaster, Nucida, Leda, 

 Malletia, Cucidlaea, Pecten, Mytiliis, Amathusia, Corbula, Pmiopea, Martesia, 

 Dentalium, Scalar ia, Galerus, Natica, Turritella, Aporrhais, Bulla. 



(4.) Magellan Region. 



Here again the exact stratigraphical relations between the Patagonian 

 formation (Miocene) and the Senonian beds has given rise to a large amount 

 of discussion, and a great divergence of opinion has been expressed. The 

 latest description of the fossils in this part of South America is by Stein- 

 maim and Wilckens.* This work, however, gives little stratigraphical in- 

 formation on the question, except that the statement is made that fossils 

 indicating the Patagonian molasse (Miocene) were obtained from the deep 

 part of a river-valley where the mapping indicates Cretaceous rocks. 



A full discussion of the stratigraphical relations of the various members 

 of the Patagonian region was written by Wilckensf in 1905. He revises 

 the opinions of those geologists who have given descriptive accounts of the 

 stratigraphical relations of the strata. Ameghino speaks of the gradual 

 transition from the Cretaceous to the Tertiary which is to be seen in Pata- 

 gonia. Ihering speaks of a gradual passage from the Cretaceous fauna to 

 that of the Patagonian formation (Miocene). Hauthal says, in opposition 

 to the statements of Steinmann, that he has found no discordance between 

 the Cretaceous and the Tertiary in south-west Patagonia. 



Wilckens, after discussing the statements of these various geologists, and 

 basing his opinion solely on their researches, concludes not only that there 

 is no gradual transition, but also that there was inserted a period of eleva- 

 tion lasting throughout the Eocene and the Oligocene. This period of 

 elevation separates the San Jorge (Upper Senonian or Danian) from the 

 Patagonian formation (Miocene). The reasons that he adduces for this 

 opinion seem rather slender. His classification appears to be mainly based 

 on the statements of Tournouer and Ameghino in regard to the relation 



* G. Steinmann and 0. Wilckens, "Kreide- und Tertiarfossilien aus den Magellans- 

 landern," Archiv for Zoologi, Stockholm, Band iv. No. 6, 1908. 



t 0. Wilckens, " Die Meeresablungerungen der Kreide- iind Tertiarformation in 

 Patagonien," Neues Jahrb. fiir Min., &c., Beii.-Band xxi, 1905, pp. 98-195. 



