458 
ON THE MEALY LINNET. 
It is needless to remind the reader that the supposition last advanced, iii° 
Yolves the possibility of numerous existing races, or species, being derived from 
a plurality of original stocks; and the variableness of the American Nightherons 
may thus, it is not unlikely, have originated in the admixture of a smaller race* 
perhaps the European. So likewise the anomalous irregularity in the number of 
tail feathers in Bewick’s Swan—eighteen or twenty—may indicate that two 
primitive races have become united * which is the more probable, in this instance, 
as, over and above certain other discordances which I have noticed in individuals 
of the same sex and parentage, the Cygnus Bewickii^ as now existing, inhabits 
alike America and Europe,whereas the Hooper Swan, which is peculiar to the eastern 
continent, is represented by an analogous but obviously distinct race in the western, 
namely the Trumpeter Swan ( C. buccinator)^ which has not hitherto been observed 
elsewhere. That many scarcely distinguishable races, however, do, at the same 
time, exist in the very same districts, apparently without intermixing, is a fact 
that has been already sufficiently descanted on. 
Now the general corollary on all the foregoing detail, I conceive to be a fair 
inference (of what is necessarily incapable of demonstration) that many true 
species, or originally-created races, exist, which it is utterly impossible to distin¬ 
guish—a conclusion of startling consequence to the student of Geology. It will be 
sufficient to mention one additional case, wherein probability strongly militates 
against the supposition of identity, but in which the most scrupulous comparison 
fails to detect a single differential character to bear out the suspicion.—I allude 
to the Common Cormorants of Europe and America. The birds of this genus, 
though remarkably powerful on the wing, and capable of long continued exertion, 
besides being able to recruit themselves by alighting on the water, are notwith¬ 
standing only met with in the near vicinity of land; and it would consequently 
be inferred, that, of races inhabiting the Atlantic coasts of Europe or America, 
those of which the range extended farthest northward would be the most likely 
to occur on both continents ; yet such is not found to be the case; inasmuch as 
Fhalacrocorax carho^ Auct., which becomes rare in the northern isles of Scotland, 
and soon disappears along the Scandinavian coast, and which in America scarcely 
reaches beyond the southernmost extremity of Labrador, is deemed to be identical 
on both shores of the ocean, whereas the European Ph^cristatus, and the American 
Ph, dilophus^ two nearly-allied but evidently distinct species, both of which 
extend to high northern latitudes, appear to. be quite confined to their respective 
continent, where each is very numerously diffused. 
I commenced this essay by entitling it a disquisition on the Mealy Linnet; 
but I have little now to say exclusively relative to that particular race, —Montes 
parturiunt, ^c. —It belongs to one of those intricate knotty groups of which I 
have spoken, comprising a number of undefinable species; though of which two, 
