Origin of Species Variorum

→ OMIT 1869 1872

I apprehend that 1859 1860 1861 1866

→ certainly 1869 1872

would have to 1859 1860 1861 1866

→ OMIT 1869 1872

from each other 1859 1860 1861 1866

→ are separated 1869 1872

of the same two groups would be distinguished 1859 1860 1861 1866

→ made a somewhat nearer 1872

quite distinct, at that period made some small 1859 1860 1861 1866

quite distinct, made at that period a somewhat nearer 1869

→ other than they now do. 1872

other. 1859 1860 1861 1866 1869

→ in italics represent 1872

represent 1859 1860 1861 1866 1869

→ a 14 , 1859 1860 1861 1866 1872

a 14 , 1869

→ q 14 , 1859 1860 1861 1866 1872

q 14 , 1869

→ p 14 , 1859 1860 1861 1866 1872

p 14 , 1869

→ b 14 1859 1860 1861 1866 1872

b 14 , 1869

→ f 14 1859 1860 1861 1866 1872

f 14 , 1869

But →OMIT in a

perfectly

....

natural classification many fossil species →certainly stand between living species, and some extinct genera between living genera, even between genera belonging to distinct families. The most common case, especially with respect to very distinct groups, such as fish and reptiles, seems to be,

that

that,

supposing them to be distinguished at the present day →OMIT by a

dozen

score of

characters, the ancient members →are separated by a somewhat lesser number of

characters,

characters;

so that the two

groups,

groups

though

....

formerly →made a somewhat nearer approach to each →other than they now do.

It is a common belief that the more ancient a form is, by so much the more it tends to connect by some of its characters groups now widely separated from each other. This remark no doubt must be restricted to those groups which have undergone much change in the course of geological ages; and it would be difficult to prove the truth of the proposition, for every now and then even a living animal, as the Lepidosiren, is

dis- covered

discovered

having affinities directed towards very distinct groups. Yet if we compare the older Reptiles and Batrachians, the older Fish, the older Cephalopods, and the eocene Mammals, with the more recent members of the same classes, we must admit that there is

some

....

truth in the remark.

Let us see how far these several facts and inferences accord with the theory of descent with modification. As the subject is somewhat complex, I must request the reader to turn to the diagram in the fourth chapter. We may suppose that the numbered letters →in italics represent genera, and the dotted lines diverging from them the species in each genus. The diagram is much too simple, too few genera and too few species being given, but this is unimportant for us. The horizontal lines may represent successive geological formations, and all the forms beneath the uppermost line may be considered as extinct. The three existing

genera,

genera

→ a 14 , → q 14 , → p 14 , will form a small family; → b 14 and → f 14 a closely allied family or sub-family; and o 14 , e 14 , m 14 , a third family. These three families, together with the many extinct genera on the several lines of descent diverging from the parent-form

(A),

(A)

will form an

order;

order,

for all will have inherited something in common from their ancient

and common

....

progenitor. On the principle of the continued tendency to divergence of character, which was formerly illustrated by this diagram, the more recent any form is, the more it will generally differ from its ancient progenitor. Hence we can understand the rule that the most ancient fossils differ most from existing forms. We must not, however, assume that divergence of character is a necessary contingency; it depends solely