Ix FAUNA HAWAIIENSIS 



Although endemicity of plant or insect, as represented by great peculiarity of 

 structure and usually by the occurrence of numbers of allied species, naturally indicates 

 a very ancient occupation of the islands by their immigrant ancestors, yet it does not 

 necessarily follow that paucity of species or the apodemicity of a genus denotes a com- 

 paratively recent immigration. A classification of the Flora, as belonging to a definite 

 age or era, based on such a supposition will certainly prove erroneous. It is not 

 probable that all immigrants, that arrive and become established, are able, even after 

 vast time, to become adapted to such diverse conditions as others, and some, doubtless, 

 are much more slow to do so than others. The evolution of new genera or species 

 would proceed in a very different manner in different cases. In judging the length of 

 time that any particular plant or group of allied plants has existed in the islands, the 

 botanist would be well advised to consider the fauna that is specially attached to these. 

 When one considers that trees little modified from foreign species, e.g. Acacia koa or 

 Sopkora cJirysophylla, possess a great endemic fauna, not only species, but even genera 

 of birds and insects, quite restricted to or dependent on them, and that some of these 

 creatures are certainly themselves not less remarkable in their peculiarities than the 

 most peculiar of the Composites or Lobelias, we may hesitate to attribute such plants 

 to a later era than many other elements of the flora, which at first sight appear far 

 more ancient. Again, while in the islands an abundant endemic fauna restricted to 

 a plant indicates an ancient occupation by the latter, the absence of such a fauna 

 does not necessarily imply the reverse. In a fauna of comparatively few types it may 

 happen that few or no species have reached the islands that could become adapted to 

 certain elements of the flora even after great length of time. I think that those who 

 are in favour of the comparatively frequent accession of immigrants to account for the 

 great series of allied species, or groups of allied genera, hardly make full allowance for 

 the great age of the islands. Hitchcock remarks in writing of the most recent portion 

 of the group, the still active Mauna Loa on Hawaii, "when one considers how little 

 the bulk of the mountain is made up of the few flows delineated on the map, and how 

 small a portion of the whole mass these can be, he is overwhelmed by the certainty 

 that there were millions of streams and that millions of years must be assumed in 

 order to say how old the mountain is. It must have commenced to build up long- 

 before the tertiary period." And here he is considering the most recent portion of the 

 group and not the vastly more ancient parts. 



For my part, as I understand it, the present Hawaiian fauna is derived from 

 waifs and strays from all directions. At rare intervals from the Eocene till now 

 chance immigrants have arrived. Some have been able to establish themselves, many 

 more probably, even after a landing has been effected, have failed. Those that have 

 been successful and have found congenial conditions have often thriven amazingly, 

 giving rise to hosts of descendant species, as they have become adapted to, or become 

 modified by, diverse conditions. There has been no 'age of Conifers' any more than 



