446 ZOOLOGICAL GEOGRAPHY. [part hi. 



The aquatic birds and waders all belong to wide-spread 

 genera, and only one or two are peculiar species." 



The Sandwich Islands thus possess a larger proportion of 

 peculiar genera and species of land-birds than any other group 

 of islands, and they are even more strikingly characterised by 

 what seems to be a peculiar family. The only other class of 

 terrestrial animals at all adequately represented on these islands, 

 are the land shells ; and here too we find a peculiar family, sub- 

 family, or genus (Achatinella or Achatinellidse) consisting of a 

 number of genera, or sub-genera,— according to the divergent views 

 of modern conchologists, — and nearly 300 species. The Eev. J. 

 T. Gulick, who has made a special study of these shells on the 

 spot, considers that there are 10 genera, some of which are con- 

 fined to single islands. The species are so restricted that their 

 average range is not more than five or six square miles, while 

 some are confined to a tract of only two square miles in extent, 

 and very few range over an entire island. Some species are 

 confined to the mountain ridges, others to the valleys ; and each 

 ridge or valley possesses its peculiar species. Considerably 

 more than half the species occur in the island of Oahu, where 

 there is a good deal of forest. Very few shells belonging to 

 other groups occur, and they are all small and obscure ; the 

 Achatinellse almost monopolising the entire archipelago. 



Remarks on the probable past history of the Sandwich Islands. 

 — The existence of these peculiar groups of birds and land- 

 shells in so remote a group of volcanic islands, clearly indicates 

 that they are but the relics of a more extensive land ; and the 

 reefs and islets that stretch for more than 1,000 miles in a west- 

 north-west direction, may be the remains of a country once 

 sufficiently extensive to develope these and many other, now 

 extinct, forms of life. 1 



Some light may perhaps be thrown on the past history of the 



1 A new genus of Beetles (Apterocyclus) of the family Lucanidse, has 

 recently been described from the Sandwich Islands, and it is said to be most 

 nearly related to a group inhabiting Chih, — an indication either of the great 

 antiquity of the fauna, or of the varied accidental migrations from which it 

 has had its origin. 



