EDITOR'S PREFACE. 7 



in the case of the "Key" the unavoidable delay has not 

 yet been overcome. The " Bibliography of Ornithology," 

 the third instalment of which protracted labor hap- 

 pily appeared in November, 1880, and the "Birds of the 

 Colorado Valley," Part II., having both been suspended 

 during publication by the same ill-timed interruption, 

 need not be considered in the present connection. But 

 a more serious difficulty, because one involving an offi- 

 cial obligation, occurred in the case of the "History of 

 North American Quadrupeds," ordered by Congress in 

 1880 to be prepared and published as Vol. XIV. of the 

 Reports of the U. S. Geological and Geographical Sur- 

 vey of the Territories, the elaboration of the text and 

 the superintendence of the drawing and engraving of 

 the necessary illustrations having continuously required 

 his attention, before, during and after the long indignity 

 to which he was subjected. 



The editor takes great pleasure in recognizing the 

 timely and valued assistance rendered in the preparation 

 of this work by his friend, Mr. H. A. Purdie, of Boston. 

 As in the case of Part L, Mr. Purdie has very kindly 

 gone over the scattered published records of the species 

 to be treated, furnishing extended memoranda, which 

 have proved an invaluable saving of time and labor ; 

 for which, as well as for important suggestions and 

 criticisms made by the same well-known ornithologist 

 in reading the proof-sheets, both author and editor are 

 greatly indebted. 



