68 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Sandy beds with boulders succeed to the shales for a few feet of 
thickness. Shales come in again above this level, rarely with striated 
pebbles. 
Fic. 17.— Section of Permian shales, boulder-beds, and sandstones at Rio 
Negro. 
The section, at the bridge (Fig. 17) above referred to, displays 
sandstones at water-level somewhat cross-bedded and carrying 
scattered pebbles and small blocks. I measured one granitic frag- 
ment 16 inches long. 
On the south side of the Rio Negro along the road going eastward 
towards Sao Bento yellow tillite beds with intercalated dark shales 
contain many granitic boulders. A cobble eight inches in diameter 
showed good striation. The boulders range from two to three feet 
ce = _ =— 
Fic. 18.— Section of fossiliferous Permian marine shales between boulder- 
beds near Rio Negro. 
in diameter, all in the yellow sandy tillite, with very few small pebbles, 
arguing for floating ice. A few kilometers along this road eastward 
from the bridge where a small stream has cut a well-defined valley in 
its descent to the Rio Negro, Dr. Oliveira found a marine fauna in 
black shales intercalated between two boulder-beds of the tillite series 
(Fig. 18). I refer to this bed and its apparent significance elsewhere. 
A few kilometers farther east by south along this road a new cut 
near the small Rio da Vida nova displayed the shales and tillite beds 
(Plates 23 and 24), at horizons closely corresponding to the beds above 
