170 THE RINGED GUILLEMOT. 



when compared with a veritable "Marrot," {Uria troile,) it presents the 

 marked distinctions of a weaker and more slender bill, and a darker shade 

 of plumage, being a fine dark olive, or, as Sir William Jardine observes, 

 "intermediate in shade between Troile and Brunnichii" besides the all- 

 important bridle. But on collecting a number of birds together, the advan- 

 tages of unlimited means of comparison become very obvious. In both the 

 differences of the bill and the colour there is an imperceptible blending, 

 till the characters assume less and less consequence, and finally are not 

 distinguishable. Further, there is an actual interchange, and thus we find 

 in some cases the Common Guillemot has the weaker bill and the darker 

 shade of plumage, from which we may ultimately argue, if we maintain 

 two species, that the common birds so marked are the rarer species which 

 have lost their bridles; while that with the coarse bill and mouse- coloured 

 garb is the commoner one, having borrowed it; in other words, that they 

 become varieties of each other. 



As regards size — another of the points which one or two writers have 

 laid hold of — the same gradual transition occurs, that is to say, we have 

 larger and smaller birds in either case. The Ringed Guillemot is said to 

 be the largest, but in both measurement and weight I have never found 

 any general advantage on either side; sometimes the one bird being heaviest, 

 and as frequently the other. Differences therefore, to be specific, must be 

 to some extent permanent and general, otherwise they cannot be considered 

 as anything beyond ordinary variety. Ornithologists, however, are not much 

 accustomed to regard varieties like the present instance, (if it be regarded 

 as such,) because if the white ring and line on the head of a Guillemot 

 be considered sufficient to recognise it as a species, we have to look for 

 that mark alone to decide, and are saved the pains of endeavouring to 

 discover whether a plain head ever had any lachrymose stripe, or when a 

 marked one acquired the distinction. 



We now come to consider the facts which lead some authors to believe 

 in the specific characters of Uria lachrymans. It is a bird having its 

 geographical range, its head quarters being Spitzbergen, where it is very 

 abundant. Coming southwards it is found breeding at various localities, 

 still in considerable numbers, becoming less numerous as we leave the 

 northern regions, until we find it very sparingly around the British coasts. 



It is said to breed in distinct colonies in high latitudes, where the 

 commoner species and Uria Brunnichii are also found in great numbers, 

 though at the Faroe Islands this habit was not noticed. Again, the young 

 bird of the first year's plumage has the peculiar white line as strongly 

 marked as in the old bird. This was observed by Professor Macgillivray, 

 and since corroborated by Mr. H. D. Graham, late of Iona, who found 

 several specimens; these he forwarded to Mr. Selby, who recognised them 



