BRITISH ASSOCIATION. 255 



closely alike in all but the colour of parts of the plumage, that it would 

 be impossible, or next to impossible, to distinguish them by any other 

 than that external mark. True, indeed, their habits are different, the 

 crow (C. corone) being a solitary bird, only few being at times collected 

 together to feed on a common carrion, while the Hooded Crow (C. cor- 

 nix) is decidedly gregarious ; but not only in an inquiry into specific 

 distinctions do we look first to external or internal marks, and postpone 

 the consideration of the habits, but even these last, if mainly considered 

 (even though there should be a close resemblance), might very likely 

 lead us astray, as in the case of the Black-backed Gull (Zarus marinus), 

 where we find the young bird, the Wagel, collecting together in num- 

 bers, but the old birds keeping aloof, singly, or at most generally, in 

 pairs, seldom more than a pair being seen together. And it is not 

 merely that it is the young birds that thus keep together as the members 

 of a family, for we see many more than these in a flock, the eggs being 

 only three in number, and that without the presence of the parents, as 

 is the case in other continuances of the family union, and, moreover, 

 I believe, until the full assumption of the adult plumage, probably the 

 third year. 



In a paper, entitled, " Remarks upon the Ringed Guillemot," read 

 before the Natural History Society of Glasgow by Robert Gray, Esq., 

 and forwarded to me by that gentleman for insertion in " The Natura- 

 list," he quotes from a statement made by J. Wolley, Esq., to the British 

 Association in the year 1850, that in the Ferroe Islands the two species 

 troile and lachrymans breed together promiscuously, in the proportion 

 of 1 to 10 ; on which a writer, E. K. B., in a subsequent letter to me 

 as the editor, observes, that it is left doubtful whether it is meant that 

 the two species breed together actually, or merely in the same situations, 

 a decision of which question would appear to decide the fact, pro or con the 

 specific identity or difference of the two species at once — " pares cum 

 paribus." It is, however, not said which is meant. But, on the other 

 hand, Mr. Proctor, Sub-Curator of the Durham University Museum, found, 

 during a visit at Grimsey, an island north of Iceland, all three species, 

 JBrunnichii, troile, and lachrymans, on separate rocks, the eggs being 

 distinguished by the natives, and each of the birds known by them under 

 different names. This latter statement, I may here observe, is corrobo- 

 rated by Mr. Arthur Strickland, who asserts that at Flamborough a few 

 of the Jlria lachrymans breed, but in places more difficult of access than 

 TJria troile, and that the egg is invariably white. Mr. Wolley, on the 

 contrary, has stated that the eggs of the two species, the present and 

 the common one, are not distinguishable. 



The late Mr. Macgillivray, in his " Manual of British Birds," speaks 

 of the ring as occurring on TJria lachrymans only in summer, and then 

 only in some individuals; but in his subsequent work, the " History of 

 British Birds," he seems anxious to make a species of it. He, however, 

 asserts that the angle of the lower mandible is farther from the base than 

 in the common species, and more prominent ; whereas it has been other- 

 wise described (by Sir William Jardine) as near to the base, and very 



