﻿CONTENTS, 



PAET IV. DECEMBER, 1860. 



ART. XII. — Descriptions of new birds of Western Africa, in the Museum of the Academy of Natural 



Sciences of Philadelphia. By John Cassin,i ...... 321 



ART. XII. — New Unionidse of the United States and Northern Mexico. By Isaac Lea, LL. D.,2 327 



ART. XIV. — Descriptions of New Species of American Tertiary and Cretaceous Fossils. By Wm. M. 



Gabb, 3 . 375 



1 Extra copies printed for the Author, ...... Nov. 1860. 



2 " " " " ...... Nov. 1860. 



3 « " " " ...... Nov. 1860. 



