THE ANIMAL LIFE OF TILE GROUP. 431 



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

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

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

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

 with minute hairs 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 Oahu^'^-^ occurs also on both Mani and Kauai, and is al)out 

 thirteen millimeters in length. Doubtless there are other species to ])e dis- 

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

 from which these interesting insects have as yet been reported. 



CHAPTER XXXIII. 

 LAND AND FRESH WATER SHELLS. 



The land shells of the Hawaiian Islands have l)een 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 w^orld has contributed 

 more really striking material for systematic study or received more attention 

 from students of evolution. 



Land Shells. 



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

 mens secured by Captain Dixon from a shell lei or necklace which Avas ])ro- 

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

 specimens back to England and described the first species as Turbo apcx-ftilva 

 in the report of his voyage round the world, which was published in 17S!». 

 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 oi- 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 thought 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 entii-e hind and fn'sh-water shell I'aiina 

 of the islands, it is the beautifully and ('ons])i('U(Misly-(M)h)i'ed trfc-dwclling 

 forms, commonly known as "tree siuiils,'" lliat arc most genci'ally soui^ht for 

 by the shell enthusiasts. Moreover, they ai'c the foi'ins upon which most of 

 the important systematic and philosophic work of the i)ast has been l)ased. Ac- 

 cording to ^Ir. E. R. Sykes. who j)ublished an extensive paper on the sul>.iect of the 

 Hawaiian jMollusca as late as 1 !)()(). at least three hundred and twentv-two of 



^^" Lepisma saccharinn. i^-' J/f(<'A(7('.v lirlfroiJiiK. ' AcIkiI iitiUidtv (st'o page 433). 



