CHANGES OF LEVEL AOL 
infers “that the land, or the whole group of Banabe, and perhaps all 
the neighbouring groups, have undergone a slight depression.” He 
also states respecting a small islet near Ualan, ‘From the description 
given of Leilei, a change of level of one or two feet would render it 
uninhabitable, and reduce it, in a short time, to the same state as the 
isle of ruins at Banabe.” 
Period of the Subsidence.—The period when these changes were in 
progress, was probably within and since the tertiary epoch. In the 
island of Metia, elevated over two hundred feet, the corals below were 
the same as those now existing, as far as we could judge from the 
fossilized specimens. At the inner margin of shore reefs, there is the 
same identity with existing genera. We do not claim to have examined 
the basement of the coral islands, and offer these facts as the only 
evidence on this point which is within reach. We cannot know with 
absolute certainty that the present races of zoophytes were not the 
successors of others of the secondary epoch: but we do know that we 
have little reason in facts observed for even the suspicion. For a 
long time volcanic action was too general and constant for the 
growth of corals: and this may have continued to interfere till a com- 
paratively late period, if we may judge from the appearance of the 
rocks, even on ‘Tahiti. 
The evidence of subsidence from coral islands might be pursued to 
other regions in other seas; but we here only refer to the facts on this 
point presented in our review of the geographical distribution of 
corals, (page 134,) since we cannot speak from personal observation. 
The subsidence has probably for a considerable period ceased in 
most if not all parts of the ocean, and subsequent elevations of many 
islands and groups have taken place, which we shall soon consider. In 
some of the Northern Carolines, the Pescadores, and perhaps some of 
the Marshall Islands, the proportion of dry land is so very small 
compared with the great extent of the atoll, that there is reason to 
suspect a slow sinking even at the present time: and it is a fact of 
special interest in connexion with it, that this region is near the axial 
line of greatest depression, where, if in any part, the action should be 
longest continued. 
Among the Kingsmills and Paumotus there is no reason whatever 
for supposing that a general subsidence is still in progress; the 
changes indicated are of a contrary character. 
The results to which we have here been led obviously differ in 
many particulars from the deductions of Mr. Darwin. 
101 
