[132] _Transactions of the Edinburgh Geological Society_, Vol. I. p. 330.

[133] _Quarterly Journal of Geological Society_, 1850, p. 96.

[134] _British Association Report_, Dundee, 1867, p. 431.

[135] The list of names was furnished to me by Dr. Guenther, and I have
added the localities from the papers containing the original descriptions,
and from Dr. Haughton's _British Freshwater Fishes_.

[136] See "The Virginia Colony of Helix nemoralis," T. D. A. Cockerell, in
_The Nautilus_, Vol. III. No. 7, p. 73.

[137] I am indebted to Mr. Mitten for this curious fact.

[138] The following remarks by Dr. Richard Spruce, who has made a special
study of mosses and especially of hepaticae, are of interest. "From what
precedes, I conclude that no existing agency is capable of transporting the
germs of our hepatics of tropical type from the torrid zone to Britain, and
I venture to suppose that their existence at Killarney dates from the
remote period when the vegetation of the whole northern hemisphere partook
of a tropical character. If I am challenged to account for their survival
through the last glacial period, I reply that, granting even the existence
of a universal ice-cap down to the latitude of 40deg in America and 50deg
in Europe, it is not to be assumed that the whole extent, even of land, was
_perennially_ entombed 'in thrilling regions of thick-ribbed ice.' Towards
the southern margin of the ice the climate was probably very similar to
that of Greenland and the northern part of Norway at the present day. The
summer sun would have great power, and on the borders of sheltered fjords
the frozen snow would disappear completely, if only for a very short
period, and I ask only for a month or two, not doubting the capacity of our
hepatics to survive in a dormant state under the snow for at least ten
months in the year. I have gathered mosses in the Pyrenees where the snow
had barely left them on August 2nd; by September 25th they were re-covered
with snow, and would not be again uncovered till the following year. The
mosses of Killarney might even enjoy a longer summer than this; for the
gulf-stream laves both sides of the south-western angle of Ireland, and its
tepid waters would exert great melting power on the ice-bound coast,
preventing at the same time any formation of ice in the sea itself." This
passage is the conclusion of a very interesting discussion on the
distribution of hepaticae in a paper on "A New Hepatic