116 Transactions 



one is forced. to is that already stated — namely, the greater number of 

 species of Australian affinities, including a large proportion of them identical 

 in island and continent, proves that trans-oceanic migration has been the 

 chief means of transport for this element. The fact of arborescent forest- 

 plants showing a high degree of endemism follows from their lessened facility 

 for dispersal compared with the other plants. 



The coastal plants, twenty-four in number, include eight shrubby 

 species. With the exception of Coprosma prisca, Hymenanthera novae- 

 zelandiae, Lepidium howei-insulae, and Cassinia tenuifolia, which are mainly 

 of New Zealand affinities, and of which three are endemic in Lord Howe 

 Island, the whole of them are found in Australia, all but two extending to 

 New Zealand and Polynesia as well. Here, probably, ocean currents bave 

 been the chief means of dispersal. 



The seeds of orchids, grasses, and sedges are probably distributed mainly 

 by wind. Of the twenty-three species found in Lord Howe Island, four are 

 endemic and related to New Zealand and Australian forms ; the remainder 

 occur in New Zealand and Australia, one or both, some extending to Poly- 

 nesia as well. The Pteridophyta, with their minute spores, probably always 

 owe their wide dispersal to wind. In Lord Howe Island there are forty-nine 

 species, the bulk of which are of wide range. The four tree-ferns and twelve 

 others are endemic and related to widely distributed species. Only one 

 non-endemic species, Blechwnn attenuatum, is Polynesian but not found 

 in Australia or New Zealand. Taking the last three groups together — 

 that is, coastal plants, orchids and grasses, and Pteridophytes — the sug- 

 gestion naturally presents itself that as distributing agencies wind and 

 ocean currents in the region of Lord Howe Island act mainly from the 

 Australian Continent eastward. Distribution in a north and south direc- 

 tion is not favoured by these means, and thus the strong New Zealand and 

 Polynesian elements in the Lord Howe Island flora demand land connections. 

 The high percentage of endemic forms in the same elements suggests that 

 such connections were severed a long time ago, while the submarine ridge 

 on which the island is situated indicates the direction in which the land 

 bridges lay. The only evidence for direct land connection between Australia 

 and Lord Howe Island is the fact that a large proportion of the Lord Howe 

 Island species of plants extend to or are related to species in Australia. 

 But a land connection with Australia since one with New Zealand or New 

 Caledonia is disproved by the fact that a deep ocean trough separates the 

 continent from the submarine ridge on which the island stands ; while the 

 coastal plants, grasses, and ferns indicate that a stream of migrants is ever 

 crossing the ocean eastwards from Australia. It will thus be seen that 

 speculations based on dynamic and biological facts may lead to opposite 

 conclusions. I have taken the former as of greatest importance in indicating 

 ancient land lines, and endeavoured to explain how the latter do not really 

 conflict with them. 



Tate, who considered Lord Howe and Norfolk Islands to form part 

 of the New Zealand region, says, " One is tempted to suggest a modern 

 immigration of Australian species which has dimmed the lustre of the 

 original flora." 



Summary : The plants of Lord Howe Island indicate former land con- 

 nections with both New Zealand and New Caledonia. The greater degree 

 of peculiarity in the New Zealand elements points to the earlier severance 

 of that connection. No closer connection with temperate Australia need be 

 postulated to explain the affinities of the flora of Lord Howe Island and 



