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→ specify one difficult case. 1872
here give a single instance of one of the cases of difficulty. 1859 1860 1861 1866
specify one such difficult case. 1869
→ elsewhere,— striking instances of which have been given by Dr. A. A. Gould in relation to the Pacific. 1869 1872
elsewhere. 1859 1860 1861 1866
↑ 1 blocks not present in 1869 1872; present in 1859 1860 1861 1866
Dr. Aug. A. Gould has given several interesting cases in regard to the land-shells of the islands of the Pacific.
→ be 1872
be, on my view, 1859 1860 1861 1866
be, according to our view, 1869
→ sometimes 1869 1872
occasionally crawl on and 1859 1860 1861 1866
→ shell, 1869 1872
of these shells was 1859 1860 1861 1866
→ having been thus treated and 1869 1872
it had 1859 1860 1861 1866
→ of average swiftness, 1869 1872
running at an average rate, 1866
→ the Helix pomatia resisted 1872
Helix pomatia 1866
OMIT 1869
→ the 1872
resisted the 1866
the Helix pomatia resisted the 1869
→ is the affinity of the species which inhabit islands 1869 1872
in regard to the inhabitants of islands, is their affinity 1859 1860 1861
in regard to islands, is the affinity 1866
→ to 1859 1860 1861 1869 1872
of their inhabitants to 1866
→ The 1869 1872
I will give only one, that of the 1859 1860 1861 1866
→ lies at the distance of between 1869 1872
between 1859 1860 1861 1866
→ of the water 1872
water 1859 1860 1861 1866
the water 1869
→specify one difficult case. Almost all oceanic islands, even the most isolated and smallest, are inhabited by land-shells, generally by endemic species, but sometimes by species found →elsewhere,— striking instances of which have been given by Dr. A. A. Gould in relation to the Pacific. ↑ Now it is notorious that land-shells are
very
....
easily killed by
salt;
sea-water;
their eggs, at least such as I have tried, sink in
sea-water
sea-water,
it
and are
killed
killed.
by
....
it.
....
Yet there must →be some unknown, but
highly
occasionally
efficient means for their transportal. Would the just-hatched young →sometimes adhere to the feet of birds roosting on the ground, and thus get transported? It occurred to me that land-shells, when hybernating and having a membranous diaphragm over the mouth of the shell, might be floated in chinks of drifted timber across moderately wide arms of the sea. And I
found
find
that several species
did
....
in this state
withstood
withstand
uninjured an immersion in sea-water during seven days: one →shell, the Helix pomatia,
and
....
after →having been thus treated and again
hybernated
hybernating
I
was
put
it in
it into
into
sea-water for twenty days, and
it
....
perfectly recovered. During this length of time
it
the shell
might have been carried by a marine
current,
current
→of average swiftness, to a distance of 660 geographical miles. As this Helix has a thick calcareous operculum, I removed it, and when it had formed a new membranous one, I again immersed it for fourteen days in sea-water, and
it
again it
recovered and crawled away. Baron Aucapitaine has
recently
since
tried similar
experi- ments:
experiments:
he placed 100 land-shells, belonging to ten species, in a box pierced with holes, and immersed it for a fortnight in the sea. Out of the hundred shells, twenty-seven recovered. The presence of an operculum seems to have been of importance, as out of twelve specimens of Cyclostoma elegans, which is thus furnished, eleven revived. It is remarkable, seeing how well →the Helix pomatia resisted with me →the salt-water, that not one
out
....
of fifty-four specimens belonging to four
species
other species
of Helix tried by Aucapitaine, recovered. It is, however, not at all probable that land-shells have often been thus transported; the feet of birds
is
offer
a more probable method.
On the Relations of the Inhabitants of Islands to those of the nearest Mainland .
The most striking and important fact for us →is the affinity of the species which inhabit islands →to those of the nearest mainland, without being actually the
same
same.
species.
....
Numerous instances could be
given
given.
of
....
this
....
fact.
law.
....
→The Galapagos Archipelago, situated under the equator, →lies at the distance of between 500 and 600 miles from the shores of South America. Here almost every product of the land and →of the water bears the unmistakeable stamp of the American continent.