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THE AMERICAN NATURALIST [Vol. XLIV 



Jersey, and some of the richest deposits are in Florida 

 and Alabama, parts which surely had a tropical climate 

 in the beginning of the Tertiary. If Patagonia was ex- 

 tratropical, we can not expect that this fanna should 

 have reached it, for its southward migration would have 

 been stopped by the southern boundary of the tropical 

 belt. 



On the other hand, von Ihering points out that, while 

 there was no immigration of tropical West Indian and 

 North American types during the Patagonian time, such 

 an immigration took place later, when the Entrerios beds 

 were deposited (which he believes to be Miocene), for we 

 find such forms in these beds. He thinks that it is thus 

 demonstrated that the destruction of Archhelenis falls in 

 the time between the deposition of the Patagonian and 

 Entrerios beds. I can not admit this, for the Patagonian 

 beds are found far to the south (between 45 and 50° S. 

 lat.), while the Entrerios beds are in 30-35° S. lat. It is 

 true, there are localities for Entrerios beds farther to the 

 south (as far as about 43° S. lat.), but of the character- 

 istic tropical types, which are named by von Ihering (on 

 p. 361) not a single one is found at these southern locali- 

 ties (see table on pp. 357 and 358). Thus it is very prob- 

 able that, while at the time and the locality of the depo- 

 sition of the Patagonian beds an extratropical climate 

 prevailed, a tropical climate may have existed at the 

 same time farther north (north of say about 40° S. lat.). 

 However, we do not know the corresponding deposits of 

 these parts, and we only know that there are tropical im- 

 migrants in later deposits in about 30-35° S. lat., but 

 this does not prove that there were no such in the north- 

 ern parts of Argentina at the time of the deposition of 

 the Patagonian beds. In fact, the presence of certain 

 tropical types in the Navidad beds of Chile (p. 514), 

 which very much resemble the Patagonian beds in gen- 

 eral character, but are situated a good deal farther 

 north, suggests strongly, that the Navidad beds 

 tropical "facies" of the Patagonian beds. I do not think 



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