422 Dwight, Black Duck of North America. [£" k 



Hylocichla guttata. Alaska Hermit Thrush. — Morion, Baca County, 

 May 3, 1905 (Warren). 



[Hylocichla guttata pallasi. Hermit Thrush. — There seems to have 

 been a misunderstanding or a mixing of specimens that served as the basis 

 of the record on which this species was admitted to the Colorado list. All 

 efforts to locate the Thome specimens have proved unavailing and it 

 seems best to withdraw the name from the State list.] 



Sialia sialis. Bluebird. — Fairly common in extreme eastern Colorado, 

 from the Arkansas River to the Platte, and breeds near Holly (Smith). 

 Noted each year at Yuma, the extreme dates of observation being April 

 18 and November 1 (Patten). Denver, eggs June 21, 1899 (Dille). 



Sialia mexicana bairdi. Chestnut-backed Bluebird. — Yuma, one 

 February 28, 1906 (Patten). 



Sialia currucoides. Mountain Bluebird. — Gaume's Ranch, Baca 

 County, common November 26-29, 1907 (Cary); Springfield, March 1-22, 

 1908 (Alexander); Yuma, February 28, 1906, and March 18, 1907 (Patten). 



THE SINGULAR CASE OF THE BLACK DUCK OF 

 NORTH AMERICA. 



BY JONATHAN DWIGHT, JR., M. D. 



The case of the Black Duck is one of extreme interest to many 

 people, partly because the species is one of the best known of 

 the North American water-fowl and partly because the naming of a 

 new race has been productive of unexpected consequences. First a 

 shuffle of the scientific names was found necessary and now the new 

 'race' itself seems to be based upon nothing more tangible than the 

 adult birds, as becomes evident from the material I have gathered. 

 The pitfalls, nomenclatural as well as ornithological, into which 

 even the most eminent authorities may fall are singularly illustrated 

 in a full discussion of the case. As yet, some facts have been missing 

 and some misinterpreted, so that the whole story needs to be retold 

 and from a new standpoint. 



Th v nomenclatural side may be very briefly dismissed here, as 

 it has already been thoroughly discussed in the pages of 'The Auk' 

 ( Vol. XXVI, April, 1909, pp. 175-179). It was in 1902 (Auk, XIX, 



