fic Islands.
19. _Peperomia._ Tropical and Sub-tropical Australia, Tropics.
20. _Piper._ Tropical and Sub-tropical Australia, Tropics.
21. _Dacrydium._ Tasmania, Malay, and Pacific Islands.
22. _Dammara._ Tropical Australia, Malay, and Pacific Islands.
23. _Dendrobium._ Tropical Australia, Eastern Tropics.
24. _Bolbophyllum._ Tropical and Sub-tropical Australia, Tropics.
25. _Sarcochilus._ Tropical and Sub-tropical Australia, Fiji, and Malay
Islands.
26. _Freycinetia._ Tropical Australia, Tropical Asia.
27. _Cordyline._ Tropical Australia, Pacific Islands.
28. _Dianella._ Australia, India, Madagascar, Pacific Islands.
29. _Cyperus._ Australia, Tropical regions mainly.
30. _Fimbristylis._ Tropical Australia, Tropical regions.
31. _Paspalum._ Tropical and Sub-tropical grasses.
32. _Isachne._ Tropical and Sub-tropical grasses.
33. _Sporobolus._ Tropical and Sub-tropical grasses.

[188] Insects are tolerably abundant in the open mountain regions, but very
scarce in the forests. Mr. Meyrick says that these are "strangely deficient
in insects, the same species occurring throughout the islands;" and Mr.
Pascoe remarked that "the forests of New Zealand were the most barren
country, entomologically, he had ever visited." (_Proc. Ent. Soc._, 1883.
p. xxix.)

[189] Introductory Essay _On the Flora of Australia_, p. 130.

[190] Hooker, _On the Flora of Australia_, p. 95.--H. C. Watson, in
Godman's _Azores_, pp. 278-286.

[191] As this is a point of great interest in its bearing on the dispersal
of plants by means of mountain ranges, I have endeavoured to obtain a few
illustrative facts:--

1. Mr. William Mitten, of Hurstpierpoint, Sussex, informs me that when the
London and Brighton railway was in progress in his neighbourhood,
_Melilotus vulgaris_ made its appearance on the banks, remained for several
years, and then altogether disappeared. Another case is that of _Diplotaxis
muralis_, which formerly occurred only near the sea-coast of Sussex, and at
Lewes; but since the railway was made has spread along it, and still
maintains itself abundantly on the railway banks though rarely found
anywhere else.

2. A correspondent in Tasmania informs me that whenever the virgin forest
is cleared in that island there invariably comes up a thick crop of a plant
locally known as fire-weed--a species of Senecio, probably _S. Australis_.
It never grows except where the fire has gone over the ground, an