OF CONCHOLOGY. 197 



DESCRIPTIONS OF FOSSILS FROM THE CLAY DEPOSITS 

 OF THE UPPER AMAZON. 



BY W. M. GABB. 



The following fossils were submitted to me by Prof. James 

 Orton, as one of the results of his late visit to South America. 

 Although there are but few species, they are sufficiently marked 

 to indicate a marine, or perhaps rather a brackish water fauna. 

 There is not sufficient material to warrant an opinion as to the 

 geological age of the deposit, though the character of fossilization, 

 and the retention of its color by one of the species, would point 

 to a very recent era. This is corroborated by the fact that this 

 latter species is a living form and common in the West Indian 

 fauna. The locality is a high bluff at Pebas, on the Ambiyacu 

 River, two miles above its confluence with the Maraiion, near the 

 Southern border of Ecuador. 



TURBONILLA, Eisso. 

 T. minuscula, Gabb.— PI. 16, fig. 1. 



Description. — Shell minute, elevated, slender ; whorls six or 

 more, rounded, suture deep ; surface marked by about fifteen 

 rounded, longitudinal ribs, with concave interspaces ; aperture 

 subcircular, outer lip simple, straight, inner lip slightly thickened. 



Dimensions. — Length, -09 in., width, 0.3 in. 



NERITINA, Lam. 

 N. pupa, Linn.— PI. 16, fig. 2. 



This familiar West Indian species occurs in the series, not 

 only characterized by its form, but fortunately retaining its pe- 

 culiar coloration in such a manner as to place its identification 

 beyond question. 



