CHAP. XV THE SANDWICH ISLANDS 313 



considerable areas of less depth, varying from two hundred 

 to a thousand fathoms, and which may therefore indicate 

 the sites of submerged islands of considerable extent. 

 When we consider that east of New Zealand and New 

 Caledonia, all the larger and loftier islands are of volcanic 

 origin, with no trace of any ancient stratified rocks 

 (except, perhaps, in the Marquesas, where, according to 

 Jules Marcou, granite and gneiss are said to occur) it 

 seems probable that the innumerable coral-reefs and atolls, 

 which occur in groups on deeply submerged banks, mark 

 the sites of bygone volcanic islands, similar to those 

 which now exist, but which, after becoming extinct, have 

 been lowered or destroyed by denudation, and finally have 

 altogether disappeared except where their sites are 

 indicated by the upward-growing coral-reefs. If this view 

 is correct we should give up all idea of there ever having 

 been a Pacific continent, but should look upon that vast 

 ocean as having from the remotest geological epochs been 

 the seat of volcanic forces, which from its profound depths 

 have gradually built up the islands which now dot its 

 surface, as well as many others which have sunk beneath 

 its waves. The number of islands, as well as the total 

 quantity of land-surface, may sometimes have been 

 greater than it is now, and may thus have facilitated the 

 transfer of organisms from one group to another, and more 

 rarely even from the American, Asiatic, or Australian 

 continents. Keeping these various facts and considera- 

 tions in view, we may now proceed to examine the fauna 

 and flora of the Sandwich Islands, and discuss the special 

 phenomena they present. 



Zoology of the Sandtvich Islands : Birds. — It need hardly 

 be said that indigenous mammalia are quite unknown in 

 the Sandwich Islands, the most interesting of the higher 

 animals being the birds, which are tolerably numerous a,nd 

 highly peculiar. Many aquatic and wading birds which 

 range over the whole Pacific visit these islands, fifty-eight 

 species having been observed, but even of these six are 

 peculiar — a cooty Fulica alai ; a moorhen, Gallinula galeata 

 var. sandvichensis ; a rail with rudimentary wings, Pen- 

 nula ecaudata ; a stilt-plover Himantopus knudseni ; and 



