From Tonga Tabu to Torres Strait. 101 



Gilbert islands to the Marshall group, and afterwards in 

 a due westerly direction through the Caroline Islands as far 

 as the Pelew Islands. The other connects the New Hebrides 

 with the Santa Cruz Islands, the Solomon Islands, New 

 Ireland, New Britain, the Admiralty Islands, and Papua. The 

 two areas of elevation, or ridges as we may call them, enclose 

 an area of depression which extends from Fiji to the Philippines, 

 and which was partially explored by the " Challenger " in the 

 months of February and March, 1875, and by the " Gazelle" in 

 June and July, 1875. The total length of this basin amounts to 

 3000 miles, and as the continent of Papua constitutes about 

 one-half of its southern boundary, it may with some show of 

 reason be distinguished by the name of the " Sea of Papua." 

 To the southward of the last-described ridge we find another area 

 of depression, which stretches from the New Hebrides to Torres 

 Strait, and forms a continuation of the 2000-fathom channel 

 between the New Hebrides and New Caledonia. This is the 

 basin represented in the Section Plate 15. Bounded on the south 

 by the shallow coral-sea whose numerous reefs crowd the space 

 between Australia and New Caledonia, it forms an almost 

 land-locked basin, communicating with the depths of the South 

 Pacific only through the above-mentioned 2000-fathom channel, 

 which also divides the Fijian plateau from New Caledonia and 

 New Zealand. The almost uniform level of the isotherms between 

 Fiji and Torres Strait, a distance of about 2000 miles, is the 

 most prominent feature of this section. It was this basin 

 —named, at the time of its discovery by the " Challenger," the 

 " Melanesian Sea" (partly on account of the dark complexion 

 of the natives of the islands by which it is surrounded, 

 partly to revive a term used by the earlier geographers and 

 navigators) — which furnished the first example of the distribu- 

 tion of temperature in a sea separated from the depths of 

 the ocean by a submarine ridge or area of elevation. The 



