228 ORVILLE A. DERBY 
A small collection brought from there by Gonzaga de Campos (15) 
represents an earthy limestone bed and one of calcareous mudstone, 
both being quite similar in appearance to some of the beds of the 
Sergipe basin. The limestone has afforded a pectinoid shell appar- 
ently identical with Neithea quadricostata Sow., which is a very 
characteristic form of the Sergipe limestone, and a small echinoid. 
The fossils from the mudstone represent species of Cucullaea, Car- 
dium, Corbula, Crassatella, Isocardia, and Tellina, closely resembling, 
if not identical with, the representatives of these genera in the beds 
of similar material of the Sergipe basin. Although no critical com- 
parison of the species could be made, there can be little doubt that 
the marine beds at Marahti represent substantially the same geo- 
logical horizon as those about Maroim, in the state of Sergipe. 
With regard to the fresh, or rather brackish, water deposits of 
the neighborhood of Bahia and other parts of the coast belt, Branner’s 
doubts of the correctness of their reference to the Cretaceous seem 
to have been based, in the first instance, on the modern aspect of 
the mollusks that occur in them, being afterward somewhat modified, 
though not entirely withdrawn, by Woodward’s statement, above 
referred to, that the vertebrate fossils are of Mesozoic types. In 
his latest reference to the subject (14) he suggests that possibly 
the vertebrate and molluscal elements of the fauna may belong to 
two distinct formations which have not been defined and separated 
from lack of proper stratigraphical and paleontological work, and 
notes appearances that suggest an unconformability between beds of 
two separate ages. Dr. I. C. White, who has also visited the typical 
locality at Monserrate Point, informs me that he also noted an 
appearance of unconformability that may possibly explain the appar- 
ent disaccord of the two fauna-elements. 
In a recent visit to Bahia the typical section was examined with 
these doubts in mind. The stratification is very confused, layers 
of conglomerate, sandstone, and shale being mingled in a most 
perplexing manner and disturbed by a number of minor folds. The 
molluscan remains occur in thin layers and detached lenses of lime- 
stone, and in no case were they found in immediate association with 
the vertebrate remains. They were, however, found both above and 
below one of the lines that best simulates an unconformable contact, 
