FOREWORD 



Dr. Cushman's present contribution upon the foraminifera, dealing 

 with the methods of study and other features of general interest, was 

 prepared at the request of the Smithsonian Institution, first as a 

 descriptive account of these minute protozoa, and second as a guide 

 to lessen the work of students who wish to pursue more detailed 

 studies of the class. The foraminifera, which are so abundant in 

 modern seas, were equally prolific during many divisions of geological 

 time, and are ideally constructed for preservation as fossils and for 

 use in stratigraphic geology. However, until recent years the students 

 of the class, employing the methods of study then in vogue, were of 

 the opinion that the specific variability of these organisms was so great 

 as to render them valueless in detailed stratigraphic work, indeed 

 some went so far as to identify present day species in rocks as far 

 back as the Early Cambrian, 



Through the efforts of members of the staff and other governmental 

 agencies, the Institution has brought together in the National Museum, 

 great collections of fossil and recent micro-organisms, particularly 

 foraminifera, bryozoa, ostracoda and diatoms, and it has long fostered 

 the scientific study of these collections in the belief that detailed 

 researches would lead to results of great practical value. This belief 

 has been happily justified, and in the case of the foraminifera. 

 Dr. Cushman's work has especially exemplified the economic results 

 arising from purely scientific studies. Not only has he proved from 

 his investigations of the National collections that the species of 

 foraminifera can be discriminated and can be depended upon in sub- 

 surface geologic investigations, but he also has made successful 

 practical applications of his scientific results. 



Charles D. Walcott, Secretary. 

 March 23, 1925. 



