12 bulletin: museum of comparative zoology: 



of the age of the Bahia beds, and this evideuce certainly points to their 

 Cretaceous or even earlier age. The evidence favoring the Tertiary 

 age of the beds, however, cannot be overlooked. Without the verte- 

 brate fossils we should have been compelled to call the Bahia sedi- 

 ments Tertiary. When, however, all the data now available are taken 

 into consideration, one of the following solutions to the problematic 

 combination seems possible : — 



I. It is possible that there are two or more well-defined formations 

 (Cretaceous and Tertiary, and possibly others), but that for lack of 

 proper stratigraphic and palaeontologic work they have not been defined 

 and separated. 



II. It is possible that both Cretaceous and Tertiary are represented, 

 but that there is no stratigraphic or faunal break between them in that 

 region. 



III. It is possible that in Brazil we have a fossil fauna unlike any 

 that characterizes eitlier Cretaceous or Tertiary of other parts of the 

 world ; that is, that some of the Tertiary forms of North America began 

 during Cretaceous times in Brazil, or that the Cretaceous forms of other 

 parts of the world survived into the Tertiary in Brazil. 



I was formerly disposed to think the first suggested solution the 

 correct one. The little I have seen of the Bahia basin inclines me to 

 think that the beds containing fossil Mollusca near the Montserrate fort 

 overlie and are northwest of the beds yielding most of the vertebrate 

 fossils. The latter beds contain heavy conglomerates at the base and 

 rest against the granites. But whether beds of two separate ages exist 

 on the coast of Brazil or not, studies of the living molluscan and coral 

 faunas of the Brazilian coast and their comparison with the faunas of 

 Florida and the West Indies lead to the inference that our gulf fauna 

 came originally from the coast of Brazil. (See Dall on Mollusca and 

 Verrill on corals.) 



It seems not improbable therefore that the Tertiary fauna of the Gulf 

 States may have originated in a similar manner on the coast of Brazil, 

 and that in migrating northward it has undergone changes that have 

 caused it to diverge somewhat from its parent stock, while the Brazilian 

 fauna of the same age may have retained some of its Cretaceous aspects. 



Since the above was written I have asked the views of Dr. A. Smith 

 Woodward. In reply to an inquiry regarding his conclusions based upon 

 the vertebrate fossils he writes under date of Xov. 7. 1902 : " I consider 

 that Lepidotus, Acrodus, Dinosaurs, and Pterodactyls prove that the 

 Bahia sandstone fauna is Mesozoic. There is, of course, some reason to 



