120 ALLEN'S NATURALIST'S LIBRARY. 



writes : "So far as is known, wherever one form occurs, both 

 in the Atlantic and Pacific, the other is found with it, the 

 proportion of Ringed Guillemots varying from one in five to 

 one in twelve of the Common Guillemot." He also states that 

 the two forms have been seen paired together, " and the white 

 line behind the eye is said to vary in length, leading to the 

 supposition that intermediate forms are found." In all the 

 specimens as yet examined by me, I have found no trace of 

 such intermediate forms, and the inter-breeding, if such there 

 be, between the Bridled and the Common Guillemot, is no 

 more than one might expect to occur between two species alike 

 in size and habits. Such instances are known to occur in other 

 groups of birds, as is evidenced by the Crows, Dippers, and 

 Wagtails. I confess, however, that I should like to have in- 

 disputable evidence that the two Guillemots inter-breed. It 

 seems to me that such satisfactory evidence must be very 

 difficult to obtain. 



There is no recorded difference in the habits or nidification 

 of the Bridled Guillemot to those of the Common Guillemot. 



III. BRUNNICH S GUILLEMOT. URIA BRUENNICHI. 



Uria brunnichii, Sabine, Trans. Linn. Soc. xii. p. 538 (1818); 

 Macgill. Brit. B. v. p. 314 (1852); Saunders, ed. Yarrell's 

 Brit. B. iv. p. 76 (1884) ; id. Man. Brit. B. p. 685 (1889) ; 

 Lilford, Col. Fig. Brit. B. part xxxii. (1896). 



Alca bruennichii, Dresser, B. Eur. viii. p. 575, pi. 622 (1877). 



Lomvia bmennichi, B. O. U. List Brit. B. p. 207 (1883). 



Alca troile brunnichi, Seebohm, Hist. Brit. B. iii. p. 388 (1885). 



Adult Male in Breeding Plumage. General colour above glossy 

 black ; the head like the back ; the lores, feathers above the 

 eye, sides of face, throat and sides of neck rich chocolate- 

 brown, contrasting with the black of the upper parts ; wings 

 black, the secondaries tipped with white, forming a wing-bar ; 

 the outer primaries with white bases to the shafts ; tail black ; 

 under surface pure white, from the lower throat downwards, a 

 sharp line of demarcation crossing to the sides of the chest, 

 and forming a blunt triangle on the lower throat ; under wing- 

 coverts white, those near the edge of the wing light brown ; 



