12 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
of the age of the Bahia beds, and this evidence 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 either 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 ow 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 Nov. 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 
