PROCEEDINQS 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. Ill, pp. 139-147. April 15, 1901. 



RESULTS OF THE BRANNER-AGASSIZ 

 EXPEDITION TO BRAZIL. 



V. 



MOLLUSKS FROM THE VICINITY OF 

 PERNAMBUCO. 



By William Healey Dall. 

 Honorary Curator, Department of Mollusks, U. S. National Museum. 



During Dr. J. C. Branner's expedition for the study of the 

 coast reefs of Northeastern Brazil collections of various inver- 

 tebrates were made. As this region is seldom visited by natu- 

 ralists and is important in the study of the geographical distri- 

 bution of the mollusks of the Western Atlantic, Dr. Branner 

 requested me to report on that part of the collection. 



Both Dr. Pilsbry and myself in listing collections of shells 

 from the Brazilian and Uruguayan coasts have been struck 

 with the predominant Antillean element among the mollusks, 

 and it seems as if the present distribution of littoral species 

 must have been largely brought about before the discharge of 

 the Amazonian watershed attained its present volume, since it is 

 difficult to imagine exclusively shore species passing the barrier 

 of several hundred miles of fresh water which intervenes be- 

 tween the present northern and southern strips of coast un- 

 affected by this mighty flood. The present collection confirms 

 the view previously taken of the very large Antillean element 

 in the fauna. Ninety-one species in all were obtained ; deduct- 



Proc. Wash. Acad. Sci., April, igoi. (139) 



