JOURNAL OF PROCEEDINGS. 673 
Lower Silurian rocks, equivalent to the Potsdam Sandstone and Calcifer- 
ous Sandrock of the New-York System. The Potsdam Sandstone is filled 
eye Limestone of the N. York System. The thickness of these strata can 
not be less than a thousand feet. The Cretaceous strata, filled with Exrogyra 
Texana, Gryphea itchert d ther Cret fossils, rest uncon- 
feet (not exceeding fifty) of Devonian rocks between. The Trenton Lime- 
stone, Group, all the Upper Silurian, nearly all the Devo- 
an, and the g, appear to be entirely wanting. niferous 
Dr. McPheeters presented a specimen of lead ore from 
Hunts’s mines, two miles from De Soto, Mo., and a fossil 
dicotyledonous leaf in ferruginous sandstone, found by Dr. 
Clark, in the neighborhood of Pike’s Peak, Kansas Ter. 
The following specimens were received from the Academy 
of Nat. Sciences of Philadelphia in exchange: casts of Radius 
and Ulna of Megalonyx Jeffersonii, and 10 casts of bones of 
the toes of the same, from the originals described by Thomas 
Jefferson, now in the cabinet of the Philadelphia Academy ; 
cus, 
and 3 bones of Dinornis, collected in New Zealand by W. 
illeeus, 
vergne, France; teeth of three species of Sharks, and verre 
and vertebra of a Cetacean, from the Red Crag, Suffolk, Eng- 
land; section of vertebra of Plesiosaurus from the = Li 
land; 3 coprolites, 2 polished, of Zethyosaurus, from = v3 
England ; teeth of Zamna from the Greensand, New Jersey ; 
50 species of Tertiary shells; 3 fragments 0. 
the Chalk of England ; scales of Lepidotus from ie Ceasin; 
e 
: he 
the thanks of the Academy to Prof. Leidy, Curator of t 
cademy of Nat. Scheneeny of Philadelphia, for this very 
ideral return, 
A Collection of Bird skins, consisting of 103 oncom ibe 
received from the Smithsonian Institution, and ee mien 
the Academy in the name of Capt. John Pope, having , 
