36 A NATURALIST IN THE PACIFIC CHAP. 



a half- forgotten thermal spring in a swamp. From this cause alone 

 I no doubt failed to find several springs. All the boiling springs 

 and those of very high temperature are probably known ; but as is 

 pointed out below it is more than likely that a large number of 

 unimportant springs remain to be discovered in many a deserted 

 inland valley and between the tide-marks along the very extensive 

 reef-bound coasts. 



As above remarked the hot springs did not come under my 

 notice in all parts of the island. They are to all appearance want- 

 ing in the western or Mbua portion, and also in the Undu portion 

 north of Natewa Bay. Taking the first-named region, it will be 

 noticed that no hot springs are indicated in the map west of the 

 Ndreketi and Wainunu rivers. I made inquiries wherever I went, 

 but with no result. On my writing to Mr. Wittstock, of Mbau- 

 lailai, who is well acquainted with the Mbua peninsula, he informed 

 me that if hot springs existed in that part of the island he would 

 probably have known of them. In that portion of the island which 

 ends in Undu Point I could neither discover nor hear of any 

 thermal springs east of Lambasa on the north side, and of Lakemba 

 on the south or Natewa Bay side ; nor could Mr. Bulling, who has 

 resided at Undu Point for many years, tell me of any springs in 

 his neighbourhood. 



On looking at the general map it will be observed that the 

 hot springs are confined to the area of basic rocks, although they 

 do not occur all over that area, not being indicated in the map to 

 the west of the Ndreketi and Wainunu rivers. They are not known 

 to occur in the region of dacites and acid andesites, as in the case 

 of the Drandramea district ; and they have not been found in the 

 area of rhyolitic and trachytic rocks that extends from Undu Point 

 to Mbuthai-sau on the north coast and to near Tawaki on the 

 Natewa Bay side. The region of hot springs would be limited on 

 the east by a line joining the Mbati-ni-kama springs with those of 

 Nandongo on the Wainikoro river and Natuvo on the north shore 

 of Natewa Bay. Such a line, though lying within it, roughly 

 indicates the limit between the regions of basic and acid rocks. 



The situation of the hot springs in the lower levels, and their 

 non-discovery at elevations exceeding 300 feet above the sea, are 

 facts of importance. In more than half the cases they arise close 

 to and often on the banks of streams and rivers, occasionally indeed 

 at the river-bottom ; and no doubt numerous unknown thermal 

 springs issue under water from the river beds. In about a third 

 of the known cases the springs come up on the coast between the 



