IiNTUODUCTIOiN. 



This paper is the fifth part of a work the intent of which is to 

 describe and illustrate the Foraminifera of the Atlantic Ocean, espe- 

 cially those species which have occurred in the waters adjacent to 

 the shores of the United States, including the whole of the Gulf of 

 Mexico and the Carribbean Sea, that being the area in which most 

 of the work of the vessels of the United States engaged in dredging 

 work has been done. This part includes the families Chilostomellidae 

 and Globigerinidae. The first part, issued in 1918, included the fam- 

 ily Astrorhizidae, the second part, issued in 1920, included the family 

 Lituolidae, the third part, issued in 1922, included the family Textu- 

 lariidae; and the fourth part, issued in 1923, included the family 

 Lagenidae. Other parts to be issued ^vill include the families Rota- 

 liidae, Nummulitidae, and Miliolidae. 



Joseph Augustine Cushman. 



