120 Transactions. 



follow Wallace in including tliem in the New Zealand region. Mr. W. L. 

 Sclater draws the line between Norfolk and Lord Howe Islands. 



If the contour of the ocean-floor be taken into account, the three above- 

 mentioned islands fall without the boundaries of the Australian region, 

 for Lord Howe Island is separated from the continent of Australia by an 

 ocean over 4,000 m. deep, but is connected with New Zealand by a sub- 

 marine ridge less than 1,800 m. below the sm-face ; whilst Norfolk Island 

 and the Kermadecs are much nearer to New Zealand than to Australia, and 

 lie on submarine ridges stretching from New Zealand to Polynesia, though 

 deeper than that reaching to Lord Howe Island. 



As regards the claim of these islands to be included in the Poly- 

 nesian region, although some Polynesian species and genera of plants 

 Teach their southern limit in one or more of them, the proportion is not 

 large enough to warrant the inclusion of the islands in that biological 

 region. 



The New Zealand biological region may be defined as including all those 

 islands in the south-west Pacific Ocean lying between the parallels of 25° 

 a,nd 60° S. lat. and the meridians of 155° E. and 175° W. long. From a 

 consideration of the distribution of the plants in New Zealand, Dr. Cockayne 

 has divided the two main islands and Stewart Island into provinces, each 

 characterized by certain floristic and ecological features (5 ; p. 313). North 

 of latitude 38° is the northern, south of latitude 42° the southern, while 

 the intermediate parts he calls the central botanical province. The islands 

 to the south of New Zealand form his subantarctic islands botanical pro- 

 vince, while the Chathams and Kermadecs each form a separate province. 

 In the section of this paper dealing with geographical distribution I have 

 endeavoured to show that Lord Howe Island, Norfolk Island, and the Ker- 

 madecs together form a natvu-al division, for which I propose the name 

 ■" subtropical islands province." 



Situated as the Kermadecs are, midway between New Zealand and the 

 Tonga Group on the southern boundary of the Polynesian region, their 

 fauna and flora are of interest alike to New Zealand biologists and students 

 of geogTaphical distribution. The geological structure of the islands, too, 

 may indicate the route and date certain Polynesian species of plants entered 

 New Zealand. The present islands do not seem to have acted as stepping- 

 stones for the passage of many plants between Tonga and New Zealand, 

 or vice, versa. Hymenophyllimi demissum and Ascarina lucida may be 

 examples of migTants in the first direction, while Melicyfi/s ranuffonts has 

 reached Eua either from Norfolk or Sunday Island. The Kermadecs are 

 the most easterly of the three groups of islands which mark the northern 

 limit of the New Zealand region, and, as they lie far from any land whence 

 they could derive their stock of plants and animals, a knowledge of their 

 flora and fauna will be interesting as showing which organisms are capable 

 of crossing wide stretches ^of ocean. As to the means of making the 

 jom-ney, some remarks are made under the heading " Geographical 

 Distribution." 



It was my intention to confine myself to a description of the plant 

 covering of the Kermadec Group, and an enumeration of the species found 

 therein ; but the affinity of the flora to that of Lord HoAve and Norfolk 

 Islands appeared to me striking, and not without significance, hence I 

 thought it advisable to preface my account with a statement of what I 

 believe to be the true position of the Kermadec Islands in the New Zealand 

 biological region, which expression in this paper will include Lord Howe 



