a r\x~ 



280 A NATURALIST ON THE "CHALLENGER 



Off the Kermadec Islands, September 14th, 1814. — We were 111 

 the morning in sight of Eaoul or Sunday Island, and Macaulay 

 Island, of the Kermadec group. No landing was effected on 

 any of the islands. This small group of islands forms with 

 New Zealand, McQuarrie Island, and the Tonga group, a direct 

 line of volcanic action, stretching about N.E., and thus at right 

 angles nearly to the north-west lines, which are followed by 

 most of the remaining Pacific groups, such as the Fijis, for 

 example. The Kermadec Islands are all very small. The flora of 

 Eaoul Island was described by Sir J. D. Hooker* from collections 

 made by Mr. MacGillivray, of H.M.S. " Herald." Forty-two 

 vascular plants are known from the islands, of which five are 

 endemic species. Half of the number consist of New Zealand 

 ferns. The large proportion of ferns in the flora is most remark- 

 able, and also their New Zealand character. There are no 

 currents leading from New Zealand towards the Kermadecs. 

 The group lies in the fork of the great current which, stretching 

 westward from the region of Ducie, Pitcairn and Tubai Islands, 

 follows the line of the Tropic of Capricorn, and branching, sends 

 its northern half to the east coast of Australia to form the East 

 Australian current, whilst its other half passes down S.W. to 

 sweep past the east coast. 



The group lies just at the northern limit of the zone of 

 westerly winds, and within that of calms and changeable winds, 

 but so close to the limit that the winds may well have trans- 

 ported many of the plants, and the preponderance of ferns 

 may be clue to the possible fact, that the winds have been the 

 main agents in the colonization of the islands, and have sufficed 

 to carry the minute fern spores, whilst heavier seeds have 

 seldom reached the island, and by other means of transport. 



If fern spores are diffused mainly by wind, it should be 

 especially difficult for them to cross the zones of constant rains, 

 and there ought to be a marked separation of fern forms in 

 distribution about those lines. 



There is no connection between the flora of the Kermadecs 

 and that of Norfolk Island, although sucli would have been 



* Sir J. D. Hooker, "Botany of Kaoul Island." Jour. Linn. Soc, Bot. 

 Vol. I., 1857, p. 125. 



