Origin of Species Variorum

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

of the orders to which they belong, 1859 1860 1861

belonging to the same group which have subsequently appeared, 1866

↑ 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.

→ or Cambrian stratum 1869

stratum 1859 1860 1861 1866 1872

→ periods 1869 1872

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

→ close of the 1869

OMIT 1872

→ rich fossiliferous deposits belonging to these assumed earliest periods, 1869

records of these vast primordial periods, 1859 1860 1861

richly fossiliferous records of these vast primordial periods, 1866

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

→belonging to the same groups which have subsequently appeared, for they

are

not

present characters

....

in any degree intermediate

between them.

in character.

↑

Consequently, if

the

theory be true, it is indisputable

that

that,

before the lowest

Cambrian

Silurian

→or Cambrian stratum was

deposited,

deposited

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

Silurian

Cambrian

age to the present day; and that during these

vast,

vast

→periods the world swarmed with living creatures. Here we encounter a formidable objection; for it seems doubtful whether the

earth,

earth

in a fit state for the habitation of living

creatures,

creatures

has lasted long enough. Sir W. Thompson concludes that the consolidation of the crust can hardly have occurred less than 20 or more than 400 million years ago, but probably not less than 98 or more than 200 million years. These very wide limits show how doubtful the data are; and other elements may have

hereafter to

be introduced into the problem. Mr. Croll estimates that about 60 million years have elapsed since the Cambrian period, but this, judging from the small amount of organic change since the commencement of the Glacial epoch,

appears

seems

a very short time for the many and great mutations of life, which have certainly occurred since the Cambrian formation; and the previous 140 million years can hardly be considered as sufficient for the development of the varied forms of life which

already

certainly

existed

during

towards

the →close of the Cambrian period.

To the question why we do not find →rich fossiliferous deposits belonging to these assumed earliest 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

the late

....

E. Forbes