Origin of Species Variorum

→ and, in so far, 1859 1860 1861

and in so far, 1866

OMIT 1869 1872

→ allied genera, which lived 1859 1860 1861 1866

allied genera existing 1872

OMIT 1869

→ and these have 1859 1860 1861 1866

allied genera, 1869

and 1872

→ a species which existed at an unknown anterior period. 1859 1860 1861 1866

some still earlier forms. 1869

some still earlier form. 1872

→ I) have 1859 1860 1861 1866

I) the species have 1869

I), a species has 1872

with slightly different grades of difference, have been subsequently discovered.

All the foregoing rules and aids and difficulties in classification

may be

are

explained, if I do not greatly deceive myself, on the view that the

Natural

natural

System

system

is founded on descent with

modification;—

modification;

that the characters which naturalists consider as showing true affinity between any two or more species, are those which have been inherited from a common parent, →and, in so far, all true classification

being

genealogical;—

genealogical;

that community of descent is the hidden bond which naturalists have been unconsciously seeking, and not some unknown plan of creation, or the enunciation of general propositions, and the mere putting together and separating objects more or less alike.

But I must explain my meaning more fully. I believe that the arrangement of the groups within each class, in due subordination and relation to

each

the

other,

other

~~groups,~~

groups,

must be strictly genealogical in order to be natural; but that the amount of difference in the several branches or groups, though allied in the same degree in blood to their common progenitor, may differ greatly, being due to the different degrees of modification which they have undergone; and this is expressed by the forms being ranked under different genera, families, sections, or orders. The reader will best understand what is meant, if he will take the trouble

to refer

of referring

to the diagram in the fourth chapter. We will suppose the letters A to L to represent →allied genera, which lived during the Silurian

epoch

epoch,

→and these have descended from →a species which existed at an unknown anterior period.

Species of

three of these genera (A, F, and →I) have transmitted modified descendants to the present day, represented by the fifteen genera ( a 14