74 REPORT or NATIONAL MUSEUM, 1921. 



Museum staff holds good to a still greater extent in the division of 

 marine invertebrates. In fact, so extensive is the number of these 

 specialists, to whom the Museum is under great obligations, that a 

 mere list of their names, with the i^articular group of invertebrates 

 the}' have undertaken to work upon, must suffice for this report. 

 It includes the following: Dr. Henry B. Bigelow (Medusae, Cteno- 

 phora). Dr. L. A. Borradaile (Crustacea: Pontoniiclae), Dr. L. R. 

 Gary (Alcyonarians), Dr. E. V. Chamberlin (x4nnelids and Gephy- 

 rea). Dr. X. A. Cobb (free-living Nematodes), Dr. Wesley R. Coe 

 (Nemerteans), Dr. Leon J. Cole (Pycnogonids), Dr. Henri Coutiere 

 (Crustacea: Crangonidae), Dr. R. P. Cowles (Phoronidea), Dr. 

 Joseph A. Cushman (Foraminifera), Prof. G. S. Dodds (fresh- 

 water Entomostraca ) , Mr. A. A. Doolittle (fresh-water Entomo- 

 straca), Prof. Max Ellis (Discodrilids), Dr. C. O. Esterly (marine 

 Copepods), Dr. A. G. Huntsman (Ascidians), Mr. Fritz Johansen 

 (fresh- water Entomostraca), Prof. Chauncey Juday (Crustacea: 

 Daphniidae), Dr. C. Dwight Marsh (fresh-water Copepods), Dr. 

 Alfred G. Mayor (Scyphomedusae), Dr. Maynard M. Metcalf 

 (Salpa, Pyrosoma, Protozoa), Dr. J. Percy Moore (Leeches), Prof. 

 J, Playfair McMurrich (Actinians), Dr. Charles C. Nutting (Hy- 

 droids), Dr. Raymond C. Osbum (Bryozoa), Dr. Henrj^ A. Pilsbrj^ 

 (Barnacles), Capt. F. A. Potts (Crustacea: Rhizocephalids) , Prof. 

 Frank Smith (Earthworms), Dr. W. M. Tattersall (Crustacea: 

 Mysidacea), Dr. Aaron L. Tread well (Annelids), Dr. Willard G. 

 Van Name (Ascidians), Prof. L. B. Walton (Planarians), Dr. 

 C. B. Wilson (parasitic Copepods). 



The division of moUusks, although less dependent on outside help, 

 nevertheless gratefully acknowledges assistance received from vari- 

 ous specialists. Thus Dr. Frank Baker, of the University of Illi- 

 nois, and Dr. Victor Sterki, of New Philadelphia, Ohio, have kindly 

 determined material. Through the kind cooperation of correspond- 

 ents several puzzling points concerning Museum material have been 

 cleared up by references to the original types or typical material in 

 the collections under their care. These correspondents are Dr. H. A. 

 Pilsbry, of the Academy of Natural Sciences in Philadelphia; Dr. 

 F. B. Loomis, of Amherst College; and Mr. W. F. Clapp, of the 

 Museum of Comparative Zoology. The Museum is under great obli- 

 gation to the United States Navy Department for cooperation of a 

 different kind, inasmuch as the investigations by Dr. Paul Bartsch, 

 curator of mollusks, into the shipworm problem were greatly expe- 

 dited through the efforts of the commanding officers of two of our 

 navy yards. The deeper understanding of the subject gained through 

 this investigation has greatly enhanced the value of our shipworm 

 material. The officers referred to are Admiral C. W. Parks, Chief 

 of the Bureau of Yards and Docks, LTnited States Navy Department ; 



