THE ZooLoGisT—JANUARY, 1875. 4279 
human wisdom to adduce all the evidence within reach, but to 
leave the verdict in the hands of that impartial jury, the working 
ornithologists. It will be seen that in this instance the evidence 
of identity is not half as strong as in the case of the two crows. 
In both instances the two supposed races are said to pair together, 
but in the crows this fact is clearly established by the presence of 
both species (?) in the same clutch; it has not been so proved in 
the guillemots. I incline to consider it an additional instance of 
that dimorphism the discovery of which seems likely to set at rest 
so many questions of specific limit. It will doubtless be observed 
that the bulk of the evidence placed on record is negative, and 
therefore inconclusive. 
“Tn its times of arrival and departure, and in its winter habits it [the ringed 
guillemot] precisely resembles the common guillemot. My remarks upon the 
plumage and the colouring of the bare parts in the one apply also with equal 
truth to the other. Both vary considerably in size, but I think upon the whole 
that the ringed guillemot is the smaller of the two. Mr. J. H. Gurney, jun., 
records the capture of a remarkably small specimen at Bridlington (Zool. 
1869, p. 1864). At various times, but mostly near the breeding season, 
I have seen couples and single birds along the coast, the couples obtained 
consisting of a male and female, but I have never seen a ringed and a plain 
bird together except in flocks, neither have I found the two of a couple to 
be of one sex. At present these facts are of little value, and before they can 
be practically applied the assistance of other resident observers will be 
required. From the latest accounts it appears that the two kinds even pair 
together; but one source of error must be kept in view, namely, that the 
same thing occurs among many species of birds, and with fertile result, 
though not always. In the case of the guillemots, who is able to declare 
that his observation of the pair has ever extended further than the act of 
pairing? One point at least I think I have settled, viz., that although 
_ (among adults?) the white marks in question may possibly be peculiar to 
very old birds, they occur in the young bird in its first plumage. After a 
vast amount of persuasion, watching, and feeing, I at last induced some of 
the people to keep both birds, giving them: liberal supplies of fish and full 
liberty to run about the cottages. Young birds were of course selected, but 
none lived as long as I could have wished; the last of the ringed birds 
living to the end of the fifth year, and the last common one only surviving 
it a few months. There was neither disappearance of the marks in the one 
case nor assumption of them in the other. Thus were much time and 
trouble wasted; for as Mr. Wolley observed (Zool. 1852, p. 8479), when 
proposing a trial of the experiment, ‘ If the ringed changed to common birds, 
or vice versa, I suppose every one would be satisfied on the fact being 
