392 A ZOOGEOGRAPHIC SCHEME FOR THE MID-PACIFIC, 



structure has been repeatedly dissected, scrutinised and pieced 

 together by two generations of geologists. Yet the result of their 

 labours has been rather the production of conflicting explanations 

 than the discovery of fundamental principles on which all might 

 agree. 



Although the zoologist might at least claim a co-heritage with 

 his geological brother in the subject of a coral atoll, but small 

 share has been taken b}' naturalists in the discussion. Yet the 

 great questions of whether the atolls of the Central Pacific repre- 

 sent the vanishing mountain tops of a drowned Trans Pacific 

 Continent or whether they are newly emerged land, should 

 present problems as pertinent to zoological as to geological 

 inquiry. And a zoologist whose attention has been claimed by 

 them should be able to pi'ovide from his special store of know- 

 ledge means for their solution which are not at the disposal of 

 his co-workers. 



On this line of inquiry it is proposed to examine the fauna of 

 Funafuti, and incidentally that of the Central Pacific, and 

 endeavour to ascertain whether it is a Continental or an Oceanic 

 Island, when and whence its fauna was derived. 



From the standpoint of Zoogeography all islands are divided 

 into two classes: Continental Islands which have been at a more 

 or less distant period united to a continent, and Oceanic Islands 

 which have never been so united. The distinction between their 

 respective fauna and flora, is that while the tirst received its 

 population by normal methods of migration, while it was a part 

 of, or at a short distance from, the mainland; the second received 

 only such animals and plants as might cross actively by flight or 

 swimming, or be borne passively across the intervening space by 

 winds or waves. Since such transmission would be easy for a few, 

 difficult for many and impossible for most, the fauna and flora of 

 an Oceanic Island will bear to an appreciative eye the distinctive 

 stamp of its selective origin. 



This idea appears to present much difficulty. For instance it 

 is concluded by one writer that, "There seems to be an argument 

 in a circle as far as oceanic insular floras are concerned. First of 



