Vor. Il, Pr. II) LOCMIS—A REVIEW OF THE TUBINARES 3 
INTRODUCTION 
THE PRESENT paper consists of six parts. Part I is a brief 
sketch of the men and writings that have been prominent in 
the advancement of our knowledge of the Tubinares. Part II 
treats of the geographic distribution of the group. Numer- 
ous distribution areas are recognized. Part III has a wider 
scope. The causes of bird migration are considered from the 
view point of the migratory movements of the Tubinares. 
Part IV relates to the variations of these birds in color, size, 
and external structure. Part V deals with their classification 
and nomenclature. Part VI is a repository of facts upon 
which the conclusions in the three preceding parts are largely 
based. It presents the results of my study of extensive series 
of the Tubinares and the outdoor observations upon this 
group made by Mr. Edward Winslow Gifford, Mr. Rollo 
Howard Beck, and Dr. Alexander Sterling Bunnell during the 
ocean expeditions sent out by the California Academy of 
Sciences. 
In the preparation of this paper I have received much as- 
sistance from institutions and individuals. For the loan of 
specimens I am indebted to Mr. Outram Bangs, Mr. A. C. 
Bent, Dr. Joseph Grinnell, Dr. Leonard C. Sanford, Mr. John 
E. Thayer, the State of Oregon Fish and Game Commission, 
through Mr. Stanley G. Jewett, the Bernice Pauahi Bishop 
Museum, through Mr. John F. G. Stokes, the Department of 
Zoology of Leland Stanford Junior University, through Prof. 
John O. Snyder, the Museum of Vertebrate Zoology of the 
University of California, through Dr. Joseph Grinnell, the 
Carnegie Museum, through Mr. W. E. Clyde Todd, and the 
United States National Museum, through Dr. Charles W. 
Richmond. I am also under obligations to Mr. L. R. Reyn- 
olds for the photographs of museum specimens reproduced in 
the accompanying illustrations, to Mr. Samuel Levi for the 
original drawing of the homolographic chart, to Mr. Edward 
Winslow Gifford for the great series of measurements, and 
lastly to my friend of many years, Mr. Ransom Pratt, who 
has read most of the manuscript of this paper during its prep- 
aration, and has made many suggestions that have added to 
the clearness of the statements. 
