age, the whole Amazonian basin
became lined with a cretaceous deposit, the margins of which crop out at
various localities on its borders. They have been observed along its
southern limits, on its western outskirts along the Andes, in Venezuela
along the shore-line of mountains, and also in certain localities near
its eastern edge. I well remember that one of the first things which
awakened my interest in the geology of the Amazonian Valley was the
sight of some cretaceous fossil fishes from the province of Ceara. These
fossil fishes were collected by Mr. George Gardner, to whom science is
indebted for the most extensive information yet obtained respecting the
geology of that part of Brazil. In this connection, let me say that here
and elsewhere I shall speak of the provinces of Ceara, Piauhy, and
Maranham as belonging geologically to the Valley of the Amazons, though
their shore is bathed by the ocean, and their rivers empty directly into
the Atlantic. But I entertain no doubt, and I hope I may hereafter be
able to show, that, at an earlier period, the northeastern coast of
Brazil stretched much farther seaward than in our day; so far, indeed,
that in those times the rivers of all these provinces must have been
tributaries of the Amazon in its eastward course. The evidence for this
conclusion is substantially derived from the identity of the deposits in
the valleys belonging to these provinces with those of the valleys
through which the actual tributaries of the Amazons flow; as, for
instance, the Tocantins, the Xingu, the Tapajos, the Madura, etc.
Besides the fossils above alluded to from the eastern borders of this
ancient basin, I have had recently another evidence of its cretaceous
character from its southern region. Mr. William Chandless, on his return
from a late journey on the Rio Purus, presented me with a series of
fossil remains of the highest interest, and undoubtedly belonging to the
cretaceous period. They were collected by himself on the Rio Aquiry, an
affluent of the Rio Purus. Most of them were found in place between the
tenth and eleventh degrees of south latitude, and the sixty-seventh and
sixty-ninth degrees of west longitude from Greenwich, in localities
varying from 430 to 650 feet above the sea-level. There are among them
remains of Mososaurus, and of fishes closely allied to those already
represented by Faujas in his description of Maestricht, and
characteristic, as is well known to geological stu