78 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



Fiji the only signs we saw of terraces were at Yangasa. The terraces 

 in Fiji are most obscure, and what we find of elevation would seem to 

 indicate sudden and rapid elevation without periods of rest such as 

 occur in the Vavau Islands of the Tonga group, or in Cuba/ where the 

 terraces are so well marked, especially in the vicinity of Cape Maysi.^ 



Lister speaks of the peculiar shape of the groups, penetrated bv lono-^ 

 narrow, and deep inlets of the sea, a condition of things very similar to 

 that of Xgillaugillah, and of the north shore of Vanua Mbalavu in 

 Fiji. Tongatabu is formed of coral limestone tliroughout, and one often 

 meets with patches of coral, many feet in diameter, on which the lines 

 of Astrceoids or Madrepores are seen radiating from a common centre. 



Lister calls attention to the basis for the growth of coral reefs which 

 can be foi-med by such islands as Falcon Island.^ He also shows that 

 in the Tonga Islands, Tongatabu and Xanuku rest on shallow banks, 

 and where the basis is exposed it is shown at Xanuku and Eua to consist 

 of layers of volcanic material laid out under water. 



Darwin and Dana both suggested that the formation of the Tonga 

 Atolls was in a period of subsidence, yet it is asserted in the discussion 

 of the subject* by Mr. J. W. Gregory that his theory (Darwin's) was 

 not proposed for areas of coral formation in shallow or rising areas. 

 Why then do Darwin and Dana quote them as examples of their theory? 

 There is altogether too much of that kind of argument in the discussion 

 of that theory. Are Darwin's supporters at liberty to carry on the 

 process of selection till nothing is left of the original statement] 



In Samoa and Tonga the volcanoes are still active, and we can, follow- 

 ing Lister, actually trace the process of elevation and of erosion which 

 has resulted in Tonga in elevating limestones and volcanic islands similar 

 in every respect to those we have observed in Fiji. Islands in the last 

 named group owe their existence to former volcanic action, the evidence 

 of which is still visible in the existence of the extinct craters of Taviuni, 

 of Thombia, of Moala, and of Totoya, and this volcanic action is to be 

 traced throughout the larger islands of the group. 



The description of Eua Island in the Tonga group given by Com- 

 mander Oldham in Nature of May 22, 1890, p. 95, applies admirably to 



1 A. Agassiz, A Reconnoissance of the Bahamas anrl the Elevated Reefs of Cuba. 

 Bull. Mus"conip. Zool., Vol. XXVI. No. 1, p. 110, 1894. 



2 R. T. Hill, Notes on the Geology of the Island of Cuba. BuU. Mas. Comp. 

 Zool,, Vol. XVI. No. 15, 189.5. 



3 Falcon Island is stated to have disappeared during an eruption in August. 

 1898. 



* Q. J. Geol. Soc. of London, Vol. XLVII. p. 590, 1891 



