INTRODUCTION. 



The present volume is the fifth of a series dealing with the Fora- 

 minifera of the North Pacific Ocean. It contains the Foraminifera 

 included in the family Rotaliidse. The first part, issued in 1910, 

 included the families Astrorhizidse and Lituolidae; the second part, 

 issued in 1911, the family Textulariidae; the third part, issued in 

 1913, the family Lagenidse; and the fourth part, issued in 1914, 

 included the families Chilostomellidse, Globigerinidas, and Nummu- 

 litidse. Part six, the last, will be devoted to the Miliolidse. 



Joseph Augustine Cushman. 



