LYBOPUPA. 227 



in the fingers under a dissecting microscope, the front of the 

 last whorl and the whole columellar side of the aperture can 

 be broken away with a needle, leaving the entire inside of the 

 outer wall of the last half whorl exposed. In fossil shells it 

 breaks off (as figured in pi. 25, figs. 2, 14, 15) . The piece may 

 then be stuck upon a slip of card for convenient examination 

 under the microscope. Care must be taken to break away 

 enough of the basal wall to show the basal fold, which is often 

 hard to see. A bull 's eye or other condenser is useful. 



In comparing specimens with the drawings it must be re- 

 membered that the apparent shape of the tubercle under the 

 inner end of the upper palatal fold changes somewhat with, 

 the angle of vision. 



The large, hollow axis is broadly open in the young, as in 

 pi. 26, fig. 8, L. spaldingi. 



Lyropupa lives on or near the ground. The sinistral species 

 inhabit the humid forest zone where they may be found on 

 mossy stones, fallen twigs and dead leaves. The dextral species 

 live in dryer open country, under stones and logs. Only dex- 

 tral forms are known from Niihau and Kahoolawe. 



Lyropupae are abundant in Pleistocene and later deposits; 

 on all the islands. They formerly occupied a far greater 

 area than at present. The forest species occurred at lower 

 levels than now, as the Achatinellas did. A good part of the- 

 low country species are now extinct, and others which are 

 abundant as fossils are rare and local as living snails. 



Twenty-two species are now recognized, nine of them de- 

 fined by former authors, Gould, Pease, Ball and Ancey. One 

 species, Vertigo striatula Pease, has not been recognized with, 

 certainty. The type specimens of all the others have been 

 examined in the preparation of this work. 



DISTRIBUTION. 16 of the 22 species are confined to single 

 islands, so far as known. 6 are common to two or more islands,, 

 but in most cases represented by special races on each. A 

 narrower view of species than we have taken would increase 

 the apparent insular endemicity but would not show inter- 

 island relationships so well. 



