564 A NATURALIST IN THE PACIFIC 



according to the synonymy accepted by some authors it is also to be 

 ascribed to America. The genus is chiefly Australian, and it is possible 

 that the littoral species may have reached America through the agency of 

 birds, since all the species of the genus possess fruits that would attract 

 frugivorous birds. 



Ipomea glaberrima (Boj.). — Old World. 



Ipomea pes capra. — Old and New Worlds. 



Vitex trifolia. — Old World. The genus is also dispersed by pigeons. 



Cassytha filiformis. — Old and New Worlds. Like Scsevola the genus is 

 chiefly Australian, and here, also, the fruits of the littoral species are not 

 only dispersed by the currents, but are known to be also disseminated by 

 fruit-pigeons. 



It is possible that birds may have taken a predominant part in the dis- 

 persal of the species of ScKvola, Vitex and Cassytha. 



There thus remain nine species for consideration. Of these two 

 are exclusively American, three are found in both the Old and New 

 Worlds and four are usually regarded as exclusively Old World plants, but 

 one of them (Colubrina asiatica) has a fair claim to be regarded as of 

 American origin. Thus it is quite possible that six out of these nine 

 plants were brought to Hawaii from America through the agency of the 

 currents. 



NOTE 37 (page 78) 



On ViviPARv IN THE Fruits of Barringtonia racemosa and 

 Carapa obovata 



As observed by me in the Rewa delta, Fiji, there was no external 

 evidence of such a process in the case of the fruits on the trees ; but I did 

 not pay very special attention to the matter, and it will be gathered from 

 Chapter XXX. that the initial stage of germination may show no indication 

 in the appearance of the fruit. More observation is needed for both 

 species. As indicated in Note 50, the structure of the seed of Barringtonia 

 racemosa is suggestive of a lost viviparous habit. With regard to Carapa, 

 Schimper (p. 43) remarks that he has never observed vivipary ; but Miquel, 

 in his Flora IndicB Batavia, particularly speaks of the seeds germinating 

 in the capsule. I think this is very likely, and that perhaps even the 

 rupture of the capsule may be partly due to this cause. 



NOTE 38 (page 78) 



On the Temperature and Density of the SuRFACE-vk^ATER of the 

 Estuaries of the Rewa River in Fiji, and of the Guayaquil 

 River in Ecuador 



(a) The Rewa Estuary. — My observations were made mostly in the 

 warm, wet seasons, from October to January, 1897-99, ^"d generally in 



