IV BULLETIN 5 0, UNITED STATES NATIONAL MUSEUM 



Part VIII, issued June 26, 1919, contains the Charadriiformes (plov- 

 er-like birds) with families Jacanidae (jacanas), Oedicnemidae (thick- 

 knees), Haematopodidae (oystercatchers), Arenariidae (turnstones), 

 Aphrizidae (surfbirds), Charadriidae (plovers), Scolopacidae 

 (snipes, sandpipers, etc.), Phalaropodidae (phalaropes), Kecurvi- 

 rostridae (avocets and stilts), Rynchopidae (skimmers), Sternidae 

 (terns), Laridae (gulls), Stercorariidae (skuas and jaegers), and 

 Alcidae (auks). 



Part IX (the present part) contains the Gruiformes with the fami- 

 lies Gruidae (cranes), Rallidae (rails, gallinules, and coots), Helior- 

 nithidae (sun-grebes), and Eurypygidae (sun-bitterns). The size of 

 the present volume has been reduced from its original bulk to permit 

 more immediate publication. 



Part X, now in course of preparation, will contain the Galliformes, 

 with the families Cracidae (guans and chachalacas), Tetraonidae 

 (grouse and ptarmigan), Phasianidae (pheasants, partridges, and 

 quail), Numididae (guinea fowl), and Meleagrididae (turkeys). 



In the nine volumes thus far published there have been treated in 

 detail (that is, with full descriptions and synonymies), besides the 

 families above mentioned and higher groups to which they belong, 

 667 genera and 2,578 species and subspecies, besides 220 extralimital 

 genera and 626 extralimital species and subspecies whose principal 

 characters are given in the keys and whose principal synonymy is given 

 in footnotes. 



Acknowledgments are due for the privilege of examining, or for 

 the loan, of specimens needed in the preparation of the present volume 

 to the authorities of the Academy of Natural Sciences of Philadel- 

 phia; American Museum of Natural History, New York; Carnegie 

 Museum, Pittsburgh; Field Museum of Natural History, Chicago; 

 Museum of Comparative Zoology, Cambridge; National Museum of 

 Canada, Ottawa; Royal Ontario Museum of Zoology, Toronto; Mu- 

 seum of Vertebrate Zoology, Berkeley; University Museum, Univer- 

 sity of Michigan, Ann Arbor; California Academy of Sciences, 

 San Francisco ; California Institute of Technology, Pasadena ; Prince- 

 ton University Museum, Princeton ; Biological Survey, Washington, 

 D. C; British Museum (Natural History), London; Museum d'His- 

 toire Naturelle, Paris; Naturhistorische Museum, Vienna; Natural 

 History Museum, Leyden; and J. H. Fleming, Toronto, and R. T. 

 Moore, Pasadena. The total number of specimens thereby made 

 available for study in the present connection is hard to estimate but 

 runs into the thousands. 



The author takes this opportunity to explain the status of his own 

 position in this work. On the death of Robert Ridgway, the late Dr. 

 Charles W. Richmond gathered together all the former's manuscripts 



