Origin of Species Variorum

→ ancestor. 1859 1860 1861 1866 1869

ancestor; and we know that such aggregated characters have especial value in classification. 1872

→ in 1859 1860 1861 1866 1869

from its allies, in 1872

→ from its allies, 1859 1860 1861 1866 1869

OMIT 1872

→ hereafter, I think, clearly 1859 1860 1861 1866

presently 1869 1872

←Subtitle not present 1859 1860 1861 Analogical Resemblances. — 1866 1869 1872

large group of beings having different habits, we may feel almost sure, on the theory of descent, that these characters have been inherited from a common →ancestor. And we know that such correlated or aggregated characters have especial value in classification.

We can understand why a species or a group of species may

depart

depart,

→in several of its most important characteristics, →from its allies, and yet be safely classed with them. This may be safely done, and is often done, as long as a sufficient number of characters, let them be ever so unimportant, betrays the hidden bond of community of descent. Let two forms have not a single character in common,

yet,

yet

if these extreme forms are connected together by a chain of intermediate

groups

groups,

we may at once infer their community of descent, and we put them all into the same class. As we find organs of high physiological importance— those which serve to preserve life under the most diverse conditions of existence— are generally the most constant, we attach especial value to them; but if these same organs, in another group or section of a group, are found to differ much, we at once value them less in our classification. We shall →hereafter, I think, clearly see why embryological characters are of such high classificatory importance. Geographical distribution may sometimes be brought usefully into play in classing large

~~and widely-distributed~~

and widely-distributed

genera, because all the species of the same genus, inhabiting any distinct and isolated region,

are

have

in all probability descended from the same parents. →

We can understand, on

the above

these

views, the very important distinction between real affinities and analogical or adaptive resemblances. Lamarck first called attention to this

subject,

distinction,

and he has been ably followed by Macleay and others. The

resemblance

resemblance,

in the shape of the body and in the fin-like anterior

limbs

limbs,

between