220 ORVILLE A. DERBY 
referred the beds of the sedimentary belt proper to the Cretaceous 
and the Tertiary; the former represented by several detached and 
somewhat disturbed basins of the fossiliferous sandstones, shales, and 
limestones; the latter, by more widespread and continuous undisturbed 
(except perhaps by vertical movements) beds of soft sands and clays 
which clearly overlie the fossiliferous ones. The recognized fossilif- 
erous (Cretaceous) basins were on the Abrolhos islands(with indeter- 
minable plant and fish remains, and associated with eruptive rocks 
that are not known elsewhere in the belt), at Bahia and vicinity, near 
Maroim, Proprid, and Santa Luzia in the state of Sergipe, and, based 
on information that was afterward proved to be reliable, near Pernam- 
buco and Parahyba. Of these basins, those of the Abrolhos and 
Bahia are of fresh (or brackish) water origin, the others being marine. 
From the Mariom district a number of typical Cretaceous fossils were 
obtained and described, but for the other localities no critical study 
of the fossils was made. Aside from lithological differences, Hartt’s 
principal criterion for discriminating the Cretaceous from the Ter- 
tiary, which had not afforded fossils, was the somewhat disturbed 
position of the former while the beds referred to the latter are 
undisturbed. 
In his expedition to the Amazonas in 1870, immediately after the 
publication of his book, Hartt dispatched two of his assistants, of whom 
the present writer was one, to Pernambuco to examine the fossiliferous 
locality reported near that place. The result was a small collection 
from the limestone rock of the small river Maria Farinha, a few miles 
north of the city, which were described by Mr. Rathbun (6), who 
referred them to the Cretaceous, without, however, finding any forms 
decidedly characteristic of that age. In 1875 Hartt personally visited the 
locality, accompanied, among others, by Dr. J. C. Branner, and secured 
a large and varied collection for the Geological Commission of Brazil, 
of which he was chief. In the following year Branner made a careful 
examination of the Sergipe basin,where a large collection was also made. 
In the same year the present writer obtained through a friend, a few 
blocks of highly fossiliferous limestone from the river Pirabas (by 
error this name was given as Piabas in the notes furnished to Dr. 
White (10) for his monograph on the Brazilian fossils), just south of 
the southern mouth of the Amazonas, containing a number of species 
