2374 The Zoologist — November, 1870. 



last of these, however, are broadly tipped with white, which white 

 portion overlies the extreme bases of the next row, blending its colour 

 with that of the latter; the anterior edge of the mirror being thus the 

 line of union of the black and white portions of these coverts, taken 

 collectively. 



In Uria Columba the row of great coverts is externally wholly black, 

 or at most the outermost feathers have only a very narrow white tip. 

 The amount of white on the feathers increases rapidly from without 

 inwards, until on the innermost there is nearly or quite as much white 

 as in U. grylle. In consequence of the small amount of white on these 

 coverts, the next row of coverts do not overlie, nor even reach it, there 

 being left a broad space of dusky between the white tips of the second 

 row of coverts and those of the first, which space rapidly diminishes 

 from the edge of the wing towards the body, forming the curved 

 crescent of dusky which is obvious upon the wing of this species. 



The mirror of Uria grylle is subject to much variation, which, how- 

 ever, never obscures its distinctive characters in any decided degree. 

 The greater coverts may be wholly dusky, then the mirror is the same 

 as before, except in its smaller size ; the next row may be tipped with 

 dusky, so that no white comes forward to coalesce with that of the 

 greater row, and an appearance like that of U. Columba is produced, 

 which need not deceive, since the dusky results from the second row 

 of coverts instead of the first: all the wing-coverts may be tipped 

 with dusky, producing a variegated or spotted mirror : finally, the 

 mirror may be only indicated by a few isolated white feathers, or may 

 be altogether wanting. It is to be borne in mind that the difference 

 in the mirror of U. grylle and Columba is only one of the most obvious 

 distinctions, but not the most specific. In the very possibly occurring 

 cases in which there is absolutely no difference between specimens in 

 this respect, the absence of the white under the wing and the shape 

 of the bill readily distinguish U. Columba from grylle. 



Perhaps no bird has so many synonyms as U. grylle. Independently 

 of its reference to divers genera, a large number of nominal species 

 have been instituted upon its various stages of plumage, some of them 

 requiring brief notice. A very common name for the species among 

 pre-Linnean writers was "Columba groenlandica" — obviously a mere 

 rendering into Latin of a popular designation. The word "grylle" 

 made an early entry into the records, designating the adult plumage. 

 Grylloides of Briinnich represents a variegated condition, and balthica 

 of the same author an immature or winter state. Lacteolus of the 



