Origin of Species Variorum

→ are separated by a space of ten degrees of latitude and are exposed to 1869 1872

inhabit a 1859 1860 1861

are separated by a space of ten degrees of latitude and live under a 1866

→ conditions; yet they are 1872

climate, and they will be found 1859 1860 1861

climate, yet they are 1866

conditions, yet they are 1869

→ climate. 1860 1861 1866 1869 1872

climate. Analogous facts could be given with respect to the inhabitants of the sea. 1859

→ The marine inhabitants of the eastern and western shores of South America are very 1869 1872

No two marine faunas are more 1859 1860 1861 1866

→ extremely few shells, crustacea or echinodermata 1872

hardly a fish, shell, or crab 1859 1860 1861 1866

extremely few fishes, shells, or crabs 1869

→ but Dr. Günther has recently shown that about thirty per cent. 1872

than those of the eastern and western shores of South and Central America; yet these great faunas are separated only by the narrow, but impassable, isthmus of Panama. 1859 1860 1861 1866

but Dr. Günther has recently shown that on opposite sides of the isthmus of Panama, about thirty percent of the fishes are the same; and this fact has led naturalists to believe that the isthmus was formerly open. 1869

→ of the fishes are the same on the opposite sides of the isthmus of Panama; and this fact has led naturalists to believe that the isthmus was formerly open. Westward of the 1872

Westward of the 1859 1860 1861 1866 1869

→ fauna. So that three marine faunas range far northward and southward in parallel lines not far from each other, under corresponding climates; but from being separated from each other by impassable barriers, either of land or open sea, they are almost wholly distinct. 1872

fauna. 1859 1860 1861 1866 1869

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

So that here three marine faunas range far northward and southward, in parallel lines not far from each other, under corresponding climates; but from being separated from each other by impassable barriers, either of land or open sea, they are wholly distinct.

conditions, yet it would not be possible to point out three faunas and floras more utterly dissimilar.

Or,

again

again,

we may compare the productions of South America south of lat.

35°

with those north of

25°,

which consequently →are separated by a space of ten degrees of latitude and are exposed to considerably different →conditions; yet they are incomparably more closely related to each

other,

other

than they are to the productions of Australia or Africa under nearly the same →climate. Analogous facts could be given with respect to the inhabitants of the sea.

A second great fact which strikes us in our general review is, that barriers of any kind, or obstacles to free migration, are related in a close and important manner to the differences between the productions of various regions. We see this in the great difference

nearly all the terrestrial productions of the New and Old Worlds, excepting in the northern parts, where the land almost joins, and where, under a slightly different climate, there might have been free migration for the northern temperate forms, as there now is for the strictly arctic productions. We see the same fact in the great difference between the inhabitants of Australia, Africa, and South America under the same

latitude:

latitude;

for these countries are almost as much isolated from each other as is possible. On each continent, also, we see the same fact; for on the opposite sides of lofty and continuous mountain-ranges,

and

....

of great deserts, and

sometimes

....

even of large rivers, we find different productions; though as mountain-chains, deserts,

&c,

&c.,

are not as impassable, or likely to have endured so

long

long,

as the oceans separating continents, the differences are very inferior in degree to those characteristic of distinct continents.

Turning to the sea, we find the same law. →The marine inhabitants of the eastern and western shores of South America are very distinct, with →extremely few shells, crustacea or echinodermata in

common,

common;

→but Dr. Günther has recently shown that about thirty per cent. →of the fishes are the same on the opposite sides of the isthmus of Panama; and this fact has led naturalists to believe that the isthmus was formerly open. Westward of the shores of America, a wide space of open ocean extends, with not an island as a halting-place for emigrants; here we have a barrier of another kind, and as soon as this is passed we meet in the eastern islands of the

Pacific,

Pacific

with another and totally distinct →fauna. So that three marine faunas range far northward and southward in parallel lines not far from each other, under corresponding climates; but from being separated from each other by impassable barriers, either of land or open sea, they are almost wholly distinct. ↑ On the other hand, proceeding still

further

farther

westward from the eastern