142 H. B. GUPPY, M.B., ON 



We have now to answer tlie question as to the manner 

 m which the Polynesian Ishinds became stocked with plants. 

 It is frequently not at all difficult to distinguish between the 

 parts played by man and other natural agents in the dis- 

 persal of plants in this region. The low coral islands and 

 the shores of the more elevated and mountainous islands are 

 occupied by plants such as Barringtonia speciosa, Calopliylhoii 

 i7iophi/Uu7n, the Mangrove, Morinda citrifolia, the Pandanus, 

 Thespesia popubiea, etc., that are known to be dispersed by 

 the currents ; and they are all plants that are widely dis- 

 tributed over the Indian and Pacific Oceans.* The only 

 doubt arises as to the particular route along which the 

 iloating seed were drifted, and if that can be established we 

 may obtain a clue as to the route pursued by the Polynesians. 

 Now a species that, like Barriiuitonia speciosa or Thespesia 

 popubiea, is almost uni\^ersal]y distributed in the tropical 

 islands of the Pacific can scarcely aid us in the matter. If, 

 however, we can find a littoral plant that has only partly 

 performed the traverse of this region, then we shall possess 

 in the interrupted operation an important piece of evidence. 

 The ]\langrove (Rhizophora. Bruguiera, etc.) is absent, or very 

 rare, in Eastern Polynesia, but unfortunately for our purpose 

 this is in great part explained by the lack of a suitable station 

 on the precipitous shores of the larger islands. We have, 

 however, in Nipa fruticans a plant well fitted for our object, 

 and one well known to be dispersed by the currents. For a 

 littoral species it has a limited range. It is found on the 

 tropical shores of Asia east of the Ganges and in the Indian 

 Archipelago, where it abounds ; and there is no question as 

 to its great antiquity in this region. Now, tlie Nipa Palm, 

 as it is sometimes termed, has attempted to reach Polynesia 

 by two routes from the Indian Archipelago, viz., by Melanesia 

 and Micronesia. Along the first route it has in the course 

 of ages reached the Solomon Islands, where I found it in 

 1884. Along the second route it has extended its range to 

 Ualan or Kusaie, at the eastern end of the Caroline Group, 

 where it was observed by Kittlitz about seventy years ago. 

 tSince its intrusion so far into the Pacific seems to have 

 escaped the notice of later botanists, and as no reference is 

 made to it by Herasley in his account of the floras of oceanic 



* Vide a paper by me on the " Dispersal of Plants," published by this 

 Society in 1890. 



