1 6 A NATURALIST IN THE PACIFIC chap. 



mangrove promontory of Lekutu which amounts to 500 or 600 

 yards. In this last case, however, much of the extension may be 

 due to the advance of the mangroves on the mud brought down 

 by the Lekutu river, so that, as far as these data show, the average 

 advance of the belt of mangroves on this coast between 1840 and 

 1895 would appear to be slight.^ 



On the other hand, the mangrove-borders of the several low 

 islands and islets, mainly formed of r&Qi-dSris, that lie off the 

 coast, have often extended themselves during this period in a marked 

 degree. The results of my comparisons are given below, the rate 

 of advance being obtained by halving the increase in length or 

 breadth as measured between the mangrove-borders, the breadth 

 being used in the long islands. 



Advance of the Mangrove- Borders of Low Islands on the North Coast of 

 Vanua Levu between 1840 and 1895. 



Thukini, or Gibson Island of Wilkes . . . 700 to 800 yards 

 Nangano, or Piner's Island of Wilkes . . 300 to 400 „ 



Nandongo, or Nuvera of Wilkes 500 „ 



Talailau (two new islands) 400 to 900 „ 



Nukunuku or Clark's Island of Wilkes . ) Not much change. 

 Thakavi, or Day's Island of Wilkes . . S 



It will be noticed that the islands of the Talailau Reef are not 

 marked in the chart of 1 840 ; they are both low mangrove islands, 

 the largest being slightly under a mile long and the smallest a 

 little under half a mile. In Nukuira Island, the Vatou of Wilkes, 

 there has been a decrease of about two-thirds of a mile during 



^ This, however, is not the case with the recent changes at the mouth ot the 

 Rewa River in Viti Levu, where the bare sandy point of Lauthala has extended 

 itseh seaward betv/een 500 and 600 yards since 1840, whilst Port Nukulau has 

 shoaled a fathom in the same period. But I can find no evidence of any marked 

 advance in the mangrove margins either towards Nukulau or on the Kamba 

 side, the only change recognisable being in the bare sandy point of Lauthala, 

 the rapid extension of which has been such as to attract the attention of resi- 

 dents, both whites and natives. Dana, who was in this locality in 1840, remarks 

 in the Geology of the U.S. Exploring Expedition, that he had learned from a 

 person who had resided there for forty years that during this period the deposits 

 had lengthened the river half a mile. When I was on the Rewa in 1897 I 

 heard that the natives in old time could see Suva Point from Rewa. This is 

 probably a native legend connected with the modern extension of Lauthala 

 Point. (The charts compared in making the above measurement of the recent 

 advance of this point were the plan of the Rewa Roads by Wilkes, in 1840, 

 and the Admiralty charts 1757 and 905, the former of which was based on 

 Lieut. Dawson's survey in 1875, the last being corrected to 1897.) 



