characters of the domestic breeds. Hence the supposed
aboriginal stocks must either still exist in the countries where they
were originally domesticated, and yet be unknown to ornithologists; and
this, considering their size, habits and remarkable characters, seems
improbable; or they must have become extinct in the wild state. But
birds breeding on precipices, and good flyers, are unlikely to be
exterminated; and the common rock-pigeon, which has the same habits with
the domestic breeds, has not been exterminated even on several of the
smaller British islets, or on the shores of the Mediterranean. Hence the
supposed extermination of so many species having similar habits with
the rock-pigeon seems a very rash assumption. Moreover, the several
above-named domesticated breeds have been transported to all parts of
the world, and, therefore, some of them must have been carried back
again into their native country; but not one has become wild or feral,
though the dovecot-pigeon, which is the rock-pigeon in a very slightly
altered state, has become feral in several places. Again, all recent
experience shows that it is difficult to get wild animals to breed
freely under domestication; yet on the hypothesis of the multiple origin
of our pigeons, it must be assumed that at least seven or eight species
were so thoroughly domesticated in ancient times by half-civilized man,
as to be quite prolific under confinement.

An argument of great weight, and applicable in several other cases, is,
that the above-specified breeds, though agreeing generally with the wild
rock-pigeon in constitution, habits, voice, colouring, and in most parts
of their structure, yet are certainly highly abnormal in other parts; we
may look in vain through the whole great family of Columbidae for a beak
like that of the English carrier, or that of the short-faced tumbler, or
barb; for reversed feathers like those of the Jacobin; for a crop like
that of the pouter; for tail-feathers like those of the fantail. Hence
it must be assumed, not only that half-civilized man succeeded in
thoroughly domesticating several species, but that he intentionally or
by chance picked out extraordinarily abnormal species; and further, that
these very species have since all become extinct or unknown. So many
strange contingencies are improbable in the highest degree.

Some facts in regard to the colouring of pigeons well deserve
consideration. The rock-pigeon is of a slaty-blue,