72 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 109 



Acknowledgments 



In 1951 the Office of Naval Research assigned a portion of funds 

 from contract N6-0NE, 243-16 (see p. 59) for transportation to 

 Washington for study at the U. S. National Museum, and in 1955 the 

 Arctic Institute of North America provided transportation for further 

 study. The division of biology of the California Institute of Tech- 

 nology defrayed part of the expenses of the photographic prints. The 

 negatives were made by G. E. MacGinitie. 



To staff members of the U. S. National Museum the writer is in- 

 debted for many courtesies and for the use of facilities for study: to 

 Dr. Remington Kellogg, Dr. Waldo L. Schmitt, Dr. Fenner A. Chace, 

 Jr., and especially to Dr. Harald A. Rehder, curator, Division of Mol- 

 lusks, and to members of his staff. (Three months were spent at the 

 Museum in 1951 and three weeks in 1955.) The writer is particularly 

 indebted to Dr. A. Myi*a Keen of Stanford University, who has been a 

 constant source of encouragement and help in many ways. During 

 February 1952 she placed the facilities of the Stanford Collection at 

 the disposal of the wi'iter. A day each was spent at the Los Angeles 

 County Museum and the California Academy of Sciences, where per- 

 mission was granted to examine the moUusk collections. The collec- 

 tion of Mr. John Q. Burch of Los Angeles was also examined. 



Dr. Gunnar Thorson of the Zoological Museum at Copenhagen has 

 been particular]}^ helpful and cooperative in sending or exchanging 

 specimens for examination, in comparing specimens with European 

 and Greenland forms, and, in some instances, searching the literature 

 for an obscure or elusive reference. 



Various individuals and librarians have been of help in looking up 

 references to which the writer did not have access: Miss Margaret 

 Irwin of the Scripps Institution of Oceanography, Dr. Ruth D. Turner 

 of the Museum of Comparative Zoology, Dr. Allyn G. Smith of the 

 California Academy of Sciences, and members of the science division 

 of the reference department of the Library of Congress. Mrs. Dorothy 

 Halmos, librarian at the Allan Hancock Foundation, has rendered 

 great assistance; and permission to use the stacks of this excellent re- 

 search library has been of inestimable help. 



By her generosity in sharing transportation. Dr. Marian H. Petti- 

 bone saved the writer much valuable time during the period spent in 

 Washington. 



Other acknowledgments are made in the text. 



