42 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
and may be fairly presumed to be of Pre-Cambrian age. In the 
coastal border gneissoid granites with well-developed augen-structure 
abound. This rock is nowhere better shown than about Rio de 
Janeiro, as in the Pao de Assucar at the entrance to the harbor. 
Apparently of later date than the granite-gneisses are intrusions of 
phonolite and tinguaite which occur in the form of stocks, while more 
basic dikes are not wanting. 
In eastern Sao Paulo there is an evidently infolded belt of slates and 
limestone, seemingly the newest member of the metamorphosed 
series. The distribution of this formation has not been shown on 
geological maps. In southeastern Santa Catharina the belt between 
the Permian border and the coast appears to be entirely granitic, 
though north of this district quartz-schists are involved in the complex 
as in the vicinity of Itajahy. 
North and south of the Permian-Triassic basin of south Brazil 
these Pre-Devonian rocks have a vast extension, stretching far into 
the interior in the state of Minas Geraes and forming the greater part 
of Uruguay. In the region south of Rio de Janeiro it is evident from 
the relations of this series to the overlying Devonian beds that one 
or more periods of deposition, mountaining-building, and igneous 
intrusion preceded the deep erosion of the deformed mass as the 
prelude to the incursion of the Devonian sea. The once eastward 
extension of this deformed and eroded Pre-Devonian terrane into 
what is now the basin of the Atlantic Ocean has no assignable limits. 
The basal beds of the Devonian rest on a westward dipping now 
slightly warped surface of these older rocks in a manner to show that 
the sea crept in over a region of little or no relief but how far this 
peneplaned surface extended to the eastward there are no definite 
facts to show. 
The Devonian Terrane-— The Devonian of south Brazil occupies 
a narrow belt of outcrop along the eastern margin of the Permian area, 
disappearing on the north in Sao Paulo and on the south in Parana. 
As strata of Devonian age reappear far to the northwest at Cuyuba 
in Matto Grosso, the Devonian is thought to extend beneath the 
Permian and Trias over a vast area. It is agreed that the Devonian 
of South Brazil includes at its base the thick, light-colored sandstones 
which form the Serrinha and the Serra das Furnas. This formation 
is overlain by fossiliferous shales of Mid-Devonian age. The De- 
vonian shales are intruded by numerous dikes and sills of diabase 
whose outcrops may be seen in the vicinity of Ponta Grossa. Their 
date of intrusion is probably Triassic. The absence of the Devonian 
