1 6 Dendy, The Chatham Islands. 



number of temperate types, however, appear to have 

 reached the Chathams along the coast from the south. 

 Such are the gigantic forget-me-not (Myosotidiinn), whose 

 occurrence elsewhere only on the Snares, south of New 

 Zealand, is extremely suggestive in this respect, and the 

 large-flowered Olearias, which are closely allied to species 

 found in the south-west of New Zealand. Probably 

 other types, shewing subtropical characters, spread 

 southwards along the coast from the north, such, for 

 example, as the Karaka or Kopi tree {Corynocarpus^^ 

 which is essentially a northern form. Thus the vegetation 

 of the Chatham Islands is largely of a coastal type, and 

 the absence of such characteristic elements of the New 

 Zealand flora as, for example, the great forest pines and 

 the evergreen beeches, may be accounted for by the exist- 

 ence of climatic barriers which they have never been able 

 to surmount. The same explanation may perhaps be 

 applied to the absence of the moas and kiwis. 



3. Sufficient time has elapsed since the islands again 

 became disconnected from the mainland to permit of the 

 origin of many new species, or at any rate varieties. This, 

 of course, has been rendered possible by the geographical 

 isolation of those plants and animals which had managed 

 to find their way to this remote region. Variation is con- 

 stantly going on amongst most species, and it is now well 

 known that when any section of a species is isolated and 

 prevented from intercrossing with the remainder of that 

 species, new varieties (and ultimately species) are likely 

 to arise ; while in the absence of some form of isolation 

 the swamping effects of intercrossing are likely to 

 preserve uniformity of character amongst the individuals 

 concerned. The importance of isolation in the develop- 

 ment of new species, ably demonstrated by such writers 

 as Gulick and Romanes, could hardly be better illustrated 

 than in the fauna and flora of the Chatham Islands. 



