204 BIRDS OF SANDWICH ISLANDS. [CH. IV 



belong to a family Drepanididae, which is absolutely 

 confined to these islands and which may have, thinks 

 Mr Wallace, affinities on the one hand to the Oriental 

 Dicoeidae and on the other to the characteristic American 

 family of Vireonidae, or Greenlet. The Passerine birds of 

 the islands are the most interesting, for two reasons; firstly 

 they comprise nearly all the peculiar genera of the islands, 

 and secondly they show a remarkable specialisation among 

 the islands. The genus Loxops, for example, of the Dre- 

 panididae has a different species in each of the islands 

 Hawai, Molokai and Mani 1 . This specialisation into pecu- 

 liar genera, and species with so restricted a range, is of 

 course correlated with the immense distance to be traversed 

 and the feeble flight of these birds when compared with 

 that of say the ducks and geese. There are however pecu- 

 liar genera among the non-Passerine birds, as the little 

 flightless Rail Pennula ecaudata. Among other peculiar 

 birds are the Sandwich Island goose, Bernicla sandvicensis, 

 and a peculiar Buzzard, Buteo solitarius. Of land and 

 fresh-water Mollusca Dr Sharp states that there are 475 

 species, all of them peculiar. Out of 1000 insects 700 are 

 peculiar ; but Dr Sharp thinks that the numbers are very 

 much less than the total will ultimately prove. 



General Observations upon the Fauna of Islands. 



We have now dealt at some length with the fauna of 

 six islands or groups of islands, A consideration of the 



1 Wilson, Aves Hawaiemis, and Rothschild, The Avifauna of Laysan. 



