PREFACE. 



Circumstances have retarded the completion of the present voUime, 

 chief among wliich were interruption by field work (including a second 

 visit to Costa Rica), occasional periods of illness, and the specially 

 difficult character of some of the included groups; furthermore, one 

 large family (the Woodpeckers, Picidse) was worked up and even set 

 in type, but was finally omitted because its inclusion would increase 

 the bidk of the volume far beyond a convenient size. It will, there- 

 fore, be included in Part VI. 



The Families included in this and preceding volumes are as follows: 



Part I, issued October 24, 1901, included the Family Fringillidse 

 (Finches) alone. 



Part II, issued October 16, 1902, included the Families Tanagridfe 

 (Tanagers), Icteridte (Troupials), Coerebidse (Honey Creepers), and 

 Mniotiltid.ie (Wood Warblers). 



Part III, published December 31, 1904, included the Motacillidse 

 (Wagtails and Pipits), Hirundinidfe (Swallows), Ampelida? (Wax- 

 wings), Ptilogonatidae (Sdky Flycatchers), Dulidse (Palm Chats), 

 Vireonidfe (A^ireos), Laniidie (Shrikes), Corvidse (Crows and Jays), 

 Paridfe (Titmice), Sittidse (Nuthatches), Certhiidse (Creepers), Trog- 

 lodytidae (Wrens), Cinclidse (Dippers), Chamaeidae (Wren-Tits), and 

 Sylviidfe (Warblers). 



Part IV, issued July 1, 1907, contained the remaining groups of 

 Oscines, namely, the Families Turdidse (Thrushes), Zeledoniidae 

 (Wren-Thrushes), Mimidae (Mockingbirds), Sturnida^ (Starlings), 

 Ploceidae (Weaver Birds), and Alaudid?e (Larks), together with the 

 Haploophonse or Oligomyodian Mesomyodi, comprising the Families 

 Oxyruncidfe (Sharp-bUls), Tyrannidse (Tyrant Flycatchers), Pipridse 

 (Manaldns), and Cotingidae (Chatterers). 



The present volume contains the Tracheophone Mesomyodi, repre- 

 sented by the Families Pteroptochidte (Tapacidos), Formicariidse 

 (Antbirds), FurnariidiE (Ovenbirds), and Dendrocolaptidse (Wood- 

 hewers), together with the Macrochires, containing the Families 

 Trochdidas (Humming Birds) and Micropodida^ (Swifts), and the 

 Heterodactylfe, represented only by the Famdy Trogonidas (Trogons). 



The number of species and subspecies described in the five volumes 

 is 2,038, with 351 additional extralimital forms characterized in the 

 "keys." About 1,150 to 1,200 forms remain to be treated in subse- 

 quent parts of the work. 



Acknowledgments for the loan of specimens for use in the prepara- 

 tion of the present volume are due to the same individuals and public 



