Origin of Species Variorum

→ 12.5, 1872

12.5, not only the true coal measures, well known to be here developed in extraordinary force, but likewise the Umbral series, which together compose 1861

12.5, 1866 1869

→ of the newer 1866 1869 1872

newer 1861

→ found much more widely extended than they appear to be, if 1872

greatly increased in size, if we could remove 1861

seen to be much more widely extended, if 1866 1869

→ were removed which 1866 1869 1872

which 1861

→ OMIT 1866 1869 1872

at the line of junction have not been metamorphosed, showing that they 1861

→ OMIT 1869 1872

marking at least sub-stages in the several successive geological epochs, 1861 1866

→ the deposits which are richest 1869 1872

our great deposits rich 1859 1860 1861 1866

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

Nature may almost be said to have guarded against the frequent discovery of her transitional or linking forms.

but, as they are rare, they may be here passed over. 1859 1860 1861

but, as they are not common, they may be here passed over. 1866

→ OMIT 1869 1872

I can see 1859 1860 1861 1866

→ can be given why 1869 1872

why 1859 1860 1861 1866

→ at its commencement and close; but I cannot 1866 1869 1872

but I can by no means pretend to 1859 1860 1861

and granitic rocks exceed, in the proportion of 19 to →12.5, the whole →of the newer Palæozoic

formation.

formations.

In many regions the metamorphic and granitic

areas

rocks

would be →found much more widely extended than they appear to be, if all the sedimentary beds →were removed which rest unconformably on them, and which →OMIT could not have formed part of the original mantle under which

the

they

granitic rocks

....

were crystallized. Hence it is probable that in some parts of the world whole

formations,

formations

→OMIT have been completely denuded, with not a wreck left behind.

One remark is here worth a passing notice. During periods of elevation the area of the land and of the adjoining shoal parts of the sea will be increased, and new stations will often be formed;— all circumstances

most

....

favourable, as previously explained, for the formation of new varieties and species; but during such periods there will generally be a blank in the geological record. On the other hand, during subsidence, the inhabited area and number of inhabitants will decrease (excepting

the productions

....

on the shores of a continent when first broken up into an archipelago), and consequently during subsidence, though there will be much extinction,

fewer

few

new varieties or species will be formed; and it is during these very periods of subsidence, that →the deposits which are richest in fossils have been accumulated. ↑

On the Absence of Numerous Intermediate Varieties in any

one

....

Single Formation .

From

the foregoing

these several

considerations

considerations,

it cannot be doubted that the geological record, viewed as a whole, is extremely imperfect; but if we confine our attention to any one formation, it becomes

much more

difficult to

under- stand,

understand,

understand

why we do not therein find closely graduated varieties between the allied species which lived at its commencement and at its close.

Some

Several

cases are on record of the same species presenting

distinct

....

varieties in the upper and lower parts of the same

formation,

formation:

→thus, Trautschold gives a number of instances with Ammonites; and Hilgendorf has described a most curious case of ten graduated forms of Planorbis multiformis in the successive beds of a fresh-water formation in Switzerland. Although each formation has indisputably required a vast number of years for its deposition, →OMIT several reasons →can be given why each should not

include

commonly include

a graduated series of links between the species which

then

....

lived;

lived

→at its commencement and close; but I cannot assign due proportional weight to the following considerations.

Although each formation may mark a very long lapse of years, each

perhaps

probably

is short compared with the period requisite to change one species into another. I am aware that two palæontologists, whose opinions are worthy of much deference, namely Bronn and