XVI PREFACE. 



Mr. J. H. Emerton, of Salem, Mass., and a few by Mr. J. S. Kingsley, of 

 the same place. They are generally larger than life, but the natural size 

 is indicated by hair-line or outline, except with such more highly mag- 

 nified details of special parts as have the natural size already indicated 

 by the other figures. The anatomical drawings were made by Mr. Em- 

 erton from preparations by Mr. Packard, and the histological illustra- 

 tions by Mr. 0. S. Minot. The lithographic plates (I to IV) were either 

 drawn by Mr. Eiley, or by Mr. Emerton under his direction. The dimen- 

 sions are expressed either in inches and the fractional parts of an inch, 

 or (of the more minute objects) in millimeters — 1 millimeter (1^"°) not 

 quite equaling 0.25 inch. The sign $ , wherever used, is an abbreviation 

 for the word "male," and the sign $ for "female." The three maps 

 were prepared by Mr. Packard. 



The Commissioners take this occasion to thank the numerous corre- 

 spondents and others who have aided in the work, and to acknowledge 

 their indebtedness to the managers of the following railroads for the 

 favor of passes over their respective lines : 



Southern Michigan and Lake Shore; Chicago, Eock Island and 

 Pacific ; Chicago, Milwaukee and Saint Paul ; Western Union ; North- 

 ern Pacific ; Saint Paul and Sioux City ; First Division Saint Paul and 

 Pacific ; Saint Paul and Pacific ; Missouri, Iowa and Nebraska ; Sioux 

 City and Pacific ; Chicago and Northwestern ; Keokuk and Des Moines ; 

 Des Moines and Fort Dodge ; Chicago, Burlington and Quincy ; Central 

 Eailroad of Iowa; Kansas Pacific; Kansas City, Saint Joseph and Coun- 

 cil Bluffs; Missouri Eiver, Fort Scott and Gulf; Saint Joseph and Den- 

 ver ; Missouri, Kansas and Texas; Atchison, Topeka and Santa Fe ; 

 Burlington and Missouri Eiver, in Nebraska; Denver and Eio Grande; 

 Texas and Pacific ; Saint Louis, Iron Mountain and Southern ; Inter- 

 national and Great Northern; Missouri Pacific; Saint Louis and San 

 Francisco ; Saint Louis, Yandalia, Terre Haute and Indianapolis ; Ohio 

 and Mississippi; Illinois Central; Galveston, Harrisburg and San An- 

 tonio ; Leavenworth, Lawrence and Galveston ; Denver Pacific ; Union 

 Pacific ; Atchison and Nebraska. 



They also take this means of acknowledging the courtesy and encour- 

 agement received from the executives of the several Western States 

 more particularly concerned, and the assistance given by the Signal 

 Bureau ; also the good services of the several special assistants em- 

 ployed, and particularly to Mr. Allen Whitman, of Saint Paul, Minn., 

 to Prof. Samuel Aughey, of Lincoln, Nebr., and to Mr. Theo. Pergande, 

 who faithfully assisted in ofiice-work at the headquarters. 



