PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 217 



breed in Greenland. Cassin in Baird's " Birds of North America " (1858) 

 placed it with query as a synonym of C. columba, and Dr. Coues, most 

 unfortunately, followed him (partly) when publishing his " Monograph 

 of the Alcidiie" (Pr. Philada. Acad. 18G8), in spite of Professor New- 

 ton's excellent indication of the species three years previous (Ibis, 18G5). 

 Since that time American Ornithologists have been silent about it. 



This seems ratl-.er singular, but is now easily explained, as, by going 

 over the ample material, I find that in most cases the American Ornith- 

 ologists bad only had the true C. mandtii before them, and that they 

 have hardly been acquainted with the true C. grylle, which it seems is 

 rather of restricted distribution in North America. They have mistaken 

 the common American bird for C. grylle for want of sufficient material 

 for comparison, being under the impression that the latter should be the 

 common form, while mancltii'Wiis generally regarded as an inhabitant of 

 the most icy and Arctic regions. Material whicli has accumulated only 

 very recently has led me to this conclusion, and also convinced me, that 

 mandtii is a perfectly good species, rather easy to distinguish and de- 

 scribe. I am thus able to fully corroborate Professor Newtown's views, 

 alluded to above. As even the history of C. columha has been involved 

 in some doubts — Schlegel placed it with grylle as a synonym — it may 

 be expedient to treat of this species also in the present connection. 



Before beginning a detailed comparison of the three species of Tyste, 

 with white wing-patches, a few general remaiks may not be out of 

 place. 



A certain distinction between the young and the adults of these 

 three species is the presence or absence of dusky at the tip of the 

 feathers forming the white wing-patch or speculum. It is not fully es- 

 tablished whether these dusky ends disappear as early as at the first 

 moult of the wing feathers following the breeding season next after 

 that in which the bird was born, or, in other words, when one year old, 

 or whether the}' first are lost in the second year, so that the bird would 

 not breed before nearly three years of age; for I do not think that the 

 Tyste breeds in the plumage with the spotted speculum, at least I never 

 saw one. To me it seems most probable that the wing-coverts become 

 white as early as the first moult, that is, when fully one year old, and 

 that they breed in the second season following that in which they were 

 boi-n. 



In the history of these species the immature birds with the dusky 

 spotted speculum have caused great confusion. Not that the young of 

 the three species are indistinguishable in this plumage, but as the 

 characters are not so i)ronounced in the immature as in the adult — as 

 usually among birds — their taking into account when comparing the 

 the species will necessarily obscure the result. If Dr. Finsch had not 

 mixed old and young ones indiscriminately together in his detailed ac- 

 count of the specific difference of grylle and mandtii, he most ])robab]y 

 M^onld have reached a result contrary to that he arrived at (2te Deutsche 



