536 COMPENDIUM OF GEOGKAPHY AND TRAVEL 



as to forbid the existence of many mammals, we find a 

 curiously rich and highly specialised avifauna, and a still 

 more astonishing development of the land moUusca. The 

 richness of the Passerine birds is most strongly marked 

 in the Drcpanididm, of which there are no less than 32 

 representatives, most of them belonging to the genera 

 Himatione and Hemignathus. The latter genus is 



HEAD OF HEMIGNATHUS. 



characterised by the extraordinary peculiarity of the 

 prolongation of the upper mandible, so that in some cases 

 it is twice the length of the lower, or even more, and the 

 genus may be regarded as a midway form between the 

 original immigrants and the more highly specialised 

 Drepanis, with long, curved, and ecpial mandibles. Until 

 recently these birds were regarded as Meliphagine, and 

 therefore as having their nearest affinities in the Australian 

 region, but Dr. Hans Gadow has recently proved con- 



