DERIVATION OF THE FLORA AND FAUNA 423 



A pesar de ([uc los volcanes . . . tienen sus formas niuy bien conservadas, no 

 existe en la tradicifni de los natives ningun recuerdo de una erupci6n. J.a isla pro- 

 duce la inipresioii de tratarse del resto de iin segmento dc un enorme volcdn central, 

 en cuya siiperfuie inclinada se han fonnado los crdtercs actualniente visibles ( omo 

 conos adventicios superiores. 



Kaster Island is sinall, hut not very small, 117 s([. km, and (il I.ICK (//^) 

 called it "the \va\c-\vorn remnant of an island that could once have claimed about 

 twice that area". Lack of time cannot have prevented the island to reach matu- 

 rity and to acquire some internal harmony of the flora and fauna. Still, they are 

 very disharmonious. The general situation of isolated islands is clearly set forth 

 by GULKK (I.e. 413-414): 



It is evident that mature groups of islands will attain an internal harmony from 

 the standpoint of the systematist. But this harmony, instead of reflecting the pre-e.\istent 

 harmony of some continental source (as is the case for continental islands or land-bridge 

 remnants), will be recognizably derivable by descent from a quite limited number of 

 original importations, at the start distinctly miscellaneous and "disharmonic", as was 

 observed to be the condition in Bermuda and St. Helena. Large series of related or 

 previously associated forms will be found from the beginning in continental islands, 

 but their counterpart must l)e brought into existence de novo if the group is truly 

 oceanic. But this distinction, obvious in theory, is in practice very difficult to recog- 

 nize, unless the oceanic condition is really extreme. 



Easter Island complies with this condition and is often described as an ex- 

 ample of a truly oceanic island; this is the general opinion, but it was told above 

 (Chapter IV) that there is no lack of theories according to which Easter is a rem- 

 nant of a land mass of continental size, a mid-Pacific continent or a land bridge 

 uniting the Australian-New Zealandic area with South America and Hawaii; Arldt, 

 Germain, Guillemin, J. W. Gregory, Meyrick, Pilsbry etc. were quoted. It 

 is not improbable that the island is the rest of a somewhat larger piece of land, 

 but this is all we can say. The bathymetrical conditions — see map — hardly tempt 

 us to construct bridges, even if not all signs of submergence are lacking. The 

 3000 m curve forms a large, almost closed crescent, on the north extremity of 

 which Easter Island rises. E.N.E. is Sala y Gomez, extending S.W.-N.E., 1200 m 

 long, 150 m broad and 30 m high, and this tiny islet is the only visible part of a 

 larger reef running in the direction N.E. 1/4 N. and called Scott Reef, where the 

 smallest depth, 1950 tn from the islet, is 35 m only; between this place and the 

 islet a series of soundings gave 55, 60, 49 and 46 m. The bank extends at least 

 a couple of km west of the islet with depths of 42 to 68 m, and nowhere within 

 this range a greater depth than 95 m was found [^iy2. 74). The scale of my map is 

 too small to give these details. Proceeding east we find, in about the same dis- 

 tance from Sala y Gomez as this is from Easter Island another submarine ridge run- 

 ning N.-S., bounded by the 1000 m curve and with depths as modest as 862 and 

 308 m. Further east again, in 97^30' w. 1., approximately, is another ridge trending 

 W.-E., where the smallest figure is 497 m. None of these shallow areas were, I 

 believe, known to the bridge-builders. They must be welcome also to those who 

 look, if not for sunken continents, at least for submerged islands used as way 

 stations in the migrations. However, all this means a possible extension east, 



