p.] 



GENERAL ACCOUNT 



OIF 



BY C. HEDLEY, Conchologist to the Australian Museum. 



THE ARCHIPELAGO. 



THE Ellice Group is an Archipelago of somewhat vague limits, 

 which trends for about four hundred miles in a north-westerly 

 and south-easterly direction, and lies between Lat. 5 35' and 

 11 20' South, and Long. 176 a and 180 East. After a gap 

 of a hundred and fifty miles, the same general trend is con- 

 tinued across the equator into the Northern Hemisphere by the 

 Gilberts, otherwise known as the Kingsmill or Line Islands, 

 whose physical features repeat those of the Ellice Group, though 

 the character of their inhabitants is widely different. 



This particular archipelago is indeed but a link in a huge chain 

 of islands which extends for about 3,500 miles from the Austral 

 Islands through the Herveys, Samoas, Ellices, and Gilberts, to 

 the Marshalls, forming the S.W. edge of that axial trough 

 described by Dana* as the Central Depression of the Pacific, 

 mapped by Whitmeef as the Great Atoll Valley, and mentioned 

 by Lapworth as " the mightiest of all the submarine buckles of 

 the earth crust ;"i the opposite N.E. edge of which is indicated 

 by the answering chain of islands stretching from Hawaii to 

 Kure. West of this Marshall- Austral chain (the " zone pacifique 

 australe " of Sacco), and roughly parallel both to it and to the 

 East Australian coast, is a second series of elevations whose 

 contour, as shown by the " Challenger's " cross sections, |j is that of 

 waves directed westward. These latter elevations have in com- 

 mon a fauna and flora characteristically continental, in contrast 

 to the essentially drift fauna and flora of the outer chain, from 

 which they are also distinguished by a system of volcanoes. The 

 term Melanesian Plateau has been proposedU as a collective 

 geographical name for these elevations, whose summits, now pro- 

 jecting as dry land, are New Zealand, Lord Howe Island, New 



* Dana Corals and Coral Islands, 1872, p. 328. 



t Encyc. Britt., (9) xix., 1885, PI. iii. 



+ Rep. Brit. Assoc. for 1892 (1893), p. 705. 



Sacco Essai sur 1'Orogenie de la Terre, Turin, 1895, p. 31. 



j| Challenger Eeports Deep Sea Deposits, 1891, Diagrams, 11, 12, 13. 



IF Hedley Proc. Linn. Soc. N.S.W. (2), vii., 1892 (1893), p. 335. 



