THE ANIMAL LIFE OF THE GROUP. 431 



several species peculiar to the islands. At least one or two among them, 

 especially the common silverfish,''*- were introduced. They are all active 

 insects that live in obscure places and, like the spring-tails, they never exhibit 

 any trace of wings. The silverfish has a distinctly segmented body, covered 

 with minute haii-s or scales, which terminate in two or three bristle-like appen- 

 dages. The four native species so far reported belong to two families and 

 have all been described from specimens collected in the native forest. The 

 native species from Oahui*^ occurs also on both Maui and Kauai, and is about 

 thirteen millimeters in length. Doubtless there are other species to be dis- 

 covered, as the mountains of the islands mentioned are the only localities 

 from which these interesting insects have as yet been reported. 



CHAPTER XXXIII. 

 LAND AND FRESH WATER SHELLS. 



Tile land shells of the Hawaiian Islands have been more extensively col- 

 lected and minutely studied than any other group of animals in the islands, 

 and it is doubtful if any single group of animals in the world has contributed 

 more really striking material for systematic study or received more attention 

 from students of evolution. 



L.VND Shells. 



The first Hawaiian land shells to be examined by Eviropeans were speci- 

 mens secured by Captain Dixon from a shell lei or necklace which was pro- 

 cured in the islands on the occasion of his memorable visit. He carried the 

 specimens back to England and descrilied the first species as Turbo apc.r-fulva 

 in the j'eport of his voyage round the world, which was published in 1789. 

 From that time to the present land shells from Hawaii have been eagerly col- 

 lected by almost every one with a taste for general natural history. 



Almost every boy in Hawaii has at one time or another made his collec- 

 tion of land shells, and a long list of scientific men and energetic collectors, 

 past and present, have given much time and tluuight to the collection and 

 study of this most interesting group of mollusks. 



While there are perhaps fifteen well-established families with as many as 

 thirty-five genera represented in the entire land and fresh-water shell fauna 

 of the islands, it is the beautifully and conspicuously-colored tree-dwelling 

 forms, commonly known as "tree snails," that are most generally .sought for 

 by the shell enthusiasts. Moreover, they are the forms upon which most of 

 the important systematic and philosophic work of the pa.st has been based. Ac- 

 cording to Mr. E. R. Sykes, who published an extensive paper on the subject of the 

 Hawaiian Mollusca as late as 1900, at least three hundred and twenty-two of 



' Mnchilis hetFroptis. ' Arfinlini-llidir (s 



