14 
April 21st. Geological Section. 
President Newberry in the chair. ‘'T'welve persons present. 
The Corresponding Secretary read by title the following 
papers, which are published in the Annals, Vol. X, Nos. 10 
and 11. 
On Prophysaon, anew Pulmonate Mollusc, on Ariolimas, 
on Helix lychnuchus, and other species. By Thomas Bland 
and W. G. Binney. (With two plates.) 
On the Physical Geography of the Bahama Islands, and 
the Distribution of Terrestrial Mollusca therein. By Thomas 
Bland. 
Pror. D. S. Martin exhibited some recently-described 
fossils from the Cretaceous of northern Texas, among which 
were Ostrea quadriplicata and belliplicata, Baculites Navarroensis, 
and Ammonites Swallowt’, (all named by Shumard,) from 
various localities in Grayson, Lamar, and Navarro counties. 
Pror. C. F. Hartt, of Cornell University, made some re- 
marks on the geological results of his recent visit to Brazil. 
The field which he had examined was chiefly the eastern 
part of the basin of the Amazonas, particularly along the 
Rio Tapajos, one of the principal southern affluents of the 
Amazon, into which it falls in about long. 22° KE. from 
Washington, This stream cuts through a considerable area 
of the Carboniferous rocks of Brazil; though the several sec- 
tions obtained were so disconnected that they were not at all 
satisfactory, in a stratigraphical point of view. 
Far up the Tapajos, the river falls over ledges of sandstone, 
of pre-carboniferous age, greatly displaced and broken by 
dikes of porphyry and trap. 
Below these falls, the Carboniferous series begins; appear- 
ing first as heavy sandstones, poor in fossils. T'o the north 
of these, are bluffs of fine black shales, also with few fossils, 
though containing some specimens related to Lepidostrobus, 
and also large septaria, with occasional ichthyodorulites and 
