2 SMITHSONIAN MISCELLANEOUS COLLECTIONS N"OL. 52 



nema in 1859. Unfortunateh' the results obtained by that writer were 

 never published in full, and the paper giving a general outline of his 

 explorations is disconnected and contains much irrelevant matter. 

 However, the general geology of the Serra do Araripe itself is quite 

 simple and its relations to the surrounding regions seem to be clear. 



The following facts are gleaned from the scanty notes of Gardner 

 and Capanema, and from those of a few others who have crossed 

 adjacent portions of Alaranhao, Piauhy, Parahyba, and Pernambuco. 



Spix and Martins refer to fossil fishes being found at Barra do Jar- 



FiG. I. — Hypothetical section across northeastern Brazil, showing the struc- 

 tural and geographical relations of the fish-bearing beds of the Serra do 

 Araripe to the coast sediments of Maranhao and Sergipe. 



dim, but it is not clear from their note (Reise in Brasilien, 11, 799) 

 that the place was visited by either of the authors. The lithographed 

 figure of a fish, Rhacolepis huccalis, published in one of the plates of 

 the atlas accompanying their work, is reproduced here. It is the 

 first one of the fossil fishes ever figured from that region (pi. vi, 

 fig. 2). 



The water-sheds between the State of Ceara and the 'States that 

 adjoin it on the south and west are mostly flat-topped table-lands or 

 plateaus. These plateaus are composed for the most part of hori- 

 zontal sedimentary beds. They rest unconformably upon schists, 

 gneisses, and granites, and at some places upon what seem to be 

 folded but unaltered Paleozoic sediments. The position, distribu- 



Fic. 2. — East-west section through the Serra do Araripe, constructed fn in the 

 notes of Gardner and Capanema. 



tion, and character of the beds show that the sediments forming the 

 plateaus formerly had a wide distribution over northeastern Brazil, 

 and that they have been gradually removed by the ordinary processes 

 of denudation. 



On the west these beds extend across Piauhy, probably with some 

 interruptions, into the State of Goyaz ; on the north they extend 

 across Piauhy and into Maranhao ; on the south they extend into 

 Bahia and Pernambuco, approaching the Rio Sao Francisco : on the 



