384 A NATURALIST IN THE PACIFIC CHAP. 



that whilst the method he describes is typical of local dispersal, the 

 other method is required in the instance of oceanic dispersal. 



ALSTONIA, an Apocynaceous genus of tropical Asia and 

 Australia, yields the caoutchouc of Fiji. Besides possessing in Fiji 

 and Samoa peculiar species, the islands of Western Polynesia 

 have in A. plumosa a species common to Fiji, Samoa, and New 

 Caledonia. Another species, A. costata, is restricted to Eastern 

 Polynesia, occurring in the different islands of the Tahitian Group 

 as well as in Rarotonga. It is possible that the Pacific species 

 may be connected with A. scholaris, a species possessing the range 

 of the genus with the exception of Polynesia. The long ciliated 

 or hairy seeds, six to nine millimetres in length, are fitted for 

 transport by the winds and in birds' plumage. The follicles 

 dehisce on the tree, and, according to Home, the light seeds are 

 distributed locally by the wind. It is probable that the thick 

 white juice oozing from a broken branch would at times aid the 

 adhesion of the seeds to a bird's feathers. 



GENIOSTOMA, a genus of the Loganiaceae, is found in Malaya, 

 Australia, and New Zealand. It possesses in G. rupestre a species 

 that ranges across the South Pacific from New Caledonia to Tahiti, 

 being associated with one or more endemic species in most of the 

 groups. The fruit is a dehiscent capsule containing numerous 

 small seeds imbedded in a yellowish pulp ; and from the stand- 

 point of dispersal it may be placed in the same category with 

 Pittosporum and Gardenia (see pages 310, 313). 



The same principle involved in the occurrence of a species 

 ranging the South Pacific from New Caledonia to Tahiti, and 

 associated with one or more endemic species in most of the 

 principal groups, is illustrated in the Euphorbiaceous genus 

 MACARANGA. It is specially noteworthy that M. tanarius, which 

 ranges from India to East Australia and the New Hebrides, comes 

 in touch in the group just named with M. harveyana, the widely- 

 ranging plant of the South Pacific above alluded to, and itself an 

 Asiatic species (see Burkill ; Bot. Chall. Exped., iii. 191 ; Index 

 Kewensis). The connection between M. harveyana, the widely- 

 ranging species of the South Pacific, and the endemic species in 

 the various groups is indicated by its affinity with M. reineckei, a 

 Samoan species. The Macarangas in Fiji grow in a variety of 

 situations, on the borders of estuaries, in the mountain forests, and 

 on the isolated mountain peaks. It is to birds that we must look 

 for the dispersal of the genus. In the case of a species, apparently 

 M. seemanni, common in the Rewa delta, the seeds, which soon fall 



