Origin of Species Variorum

→ numbers of species 1859 1860 1861 1866

many species in several 1869

species belonging to several 1872

→ same group 1866

same group, 1859 1860 1861

main divisions of the animal kingdom 1869 1872

→ Silurian trilobites have 1859 1860 1861 1866

Silurian trilobites are 1869

Cambrian and Silurian trilobites are 1872

→ belonging to the same group which have subsequently appeared, 1866

of the orders to which they belong, 1859 1860 1861

belonging to the same groups which have subsequently appeared, 1869 1872

↑ 1 blocks not present in 1866 1869 1872; present in 1859 1860 1861

If, moreover, they had been the progenitors of these orders, they would almost certainly have been long ago supplanted and exterminated by their numerous and improved descendants.

→ stratum 1859 1860 1861 1866 1872

or Cambrian stratum 1869

→ yet quite unknown, periods of time, 1859 1860 1861 1866

periods 1869 1872

→ richly fossiliferous records of these vast primordial periods, 1866

records of these vast primordial periods, 1859 1860 1861

rich fossiliferous deposits belonging to these assumed earliest periods, 1869

rich fossiliferous deposits belonging to these assumed earliest periods prior to the Cambrian system, 1872

→ OMIT 1866 1869 1872

of the most 1859 1860 1861

→ were until recently 1866 1869 1872

are 1859 1860 1861

the

sudden

appearance

Appearance

groups

Groups

Allied

allied

Species

the

lowest

known

fossiliferous

Fossiliferous

strata .—

Strata .

There is another and allied difficulty, which is much

graver.

more serious.

I allude to the manner in which →numbers of species of the →same group suddenly appear in the lowest known fossiliferous rocks. Most of the arguments which have convinced me that all the existing species of the same group

are

have

descended from

a single

one

progenitor, apply with

~~nearly~~

nearly

equal force to the earliest known species. For instance,

cannot

be doubted

doubt

that all the →Silurian trilobites have descended from some one crustacean, which must have lived long before the

Cambrian

Silurian

age, and which probably differed greatly from any known animal. Some of the most ancient

~~Silurian~~

Silurian

animals, as the Nautilus, Lingula,

&c,

&c.,

do not differ much from living species; and it cannot on

our

theory be supposed, that these old species were the progenitors of all the species →belonging to the same group which have subsequently appeared, for they

are

not

~~present characters~~

present characters

in any degree intermediate

in character.

between them.

↑

Consequently, if

the

theory be true, it is indisputable

that

that,

before the lowest

Cambrian

Silurian

→stratum was

deposited

deposited,

long periods elapsed, as long as, or probably far longer than, the whole interval from the

Cambrian

Silurian

age to the present day; and that during these

vast

vast,

→yet quite unknown, periods of time, the world swarmed with living creatures.

To the question why we do not find →richly fossiliferous records of these vast primordial periods, I can give no satisfactory answer. Several →OMIT eminent geologists, with Sir R. Murchison at their head, →were until recently convinced that we

see

beheld

in the organic remains of the lowest Silurian stratum the

dawn

life.

~~this~~

~~planet.~~

Other highly competent judges, as Lyell and