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AMERICAN JOURNAL 



A common species of a very rude aspect, easily distinguished 

 by its rude, irregular lamellar ribs. We found examples in sev- 

 eral different villages ; all found on the ground in damp woods. 



Pitys decorticata, Garrett. Plate 19, fig. 19. 



Shell subdiscoid, openly umbilicate, thin, subpellucid, cinere- 

 ous, under a brownish horn-colored epidermis, adults decorticated, 

 rarely with radiating dashes of reddish brown, arcuately ribbed, 

 ribs lamellar, regular, rather closely set, continued on the base, 

 interstices very finely striated ; spire flatly convex ; suture chan- 

 neled ; whorls 5, convex, slowly increasing, last one convexly 

 declivous above, rounded beneath, obsoletely angular on the 

 periphery ; umbilicus deep, exposing the whorls, about a fourth 

 the diameter of the shell ; aperture oblique, orbicular luniform ; 

 peristome thin, simple ; parietal region very thinly callosed. 



Diam., 4 mill. ; height, 2 mill 



Habitat, Rarotonga Id., Cook's Isles. (Coll. Garrett and Phila. 

 Acad.) 



A common species found on the ground in a mountain ravine. 



Pitys Harveyensis, Garrett. Plat 19, fig. 20. 



Shell subdiscoid, umbilicate, thin, subpellucid, greenish-ash, 

 with reddish-brown arcuate tessellations, closely and very finely 

 plicately striated, striae oblique, sinuous, less developed on the 

 base ; spire flatly convex : suture channeled ; whorls 5, flatly 

 convex, slowly and regularly increasing, last one obtusely angu- 

 lar, slanting above, convex beneath ; umbilicus moderate, deep, 

 exhibiting the whorls, one-fourth the diameter of the shell ; aper- 

 ture orbicular-luniform, oblique ; peristome thin, simple. 



Diam., 4^ mill. ; height, 2 mill. 



Habitat, Rarotonga Id., Cook's Isles. (Coll. Garrett and Phila. 

 Acad.) 



A common species found under rotten wood. 



Pitys OTAREiE, Garrett. Plate 19, fig. 21. 



Shell umbilicate, subdiscoid, thin, subpellucid, dark brown, 

 plicately striated, striae closely set, sinuous, oblique, finer and 

 more crowded beneath ; spire flatly convex, suture channeled ; 

 whorls 5, convex, regularly and moderately increasing, last one 

 rounded ; umbilicus large, perspective, rather freely showing the 

 whorls, one-third the diameter of the shell; aperture oblique, 

 roundly lunate ; peristome thin, simple ; columella thin, slightly 

 expanded above. 



