234 PROCEEDINGS OF THE ACADEMY OP 



lated with dark-brown, and sometimes tlie body adorned with 

 zigzag stripes ; spire convex, apex flat ; suture rather deeply im- 

 pressed ; whorls 6^, rounded, regularly and slowly increasing, the 

 last one slanting from the shoulder towards the base ; umbilicus 

 small, but deep, about one-fifth the greatest diameter of the shell ; 

 aperture vertical, narrow, luniform, fauces with four, columella 

 with one, and the parietal region with three lamellae; peristome 

 thin, simple. 



Diam. 3, height 1^ mill. 



Hah. Maupiti I., Society Isles. (Coll. Phil. Acad. Xat. Sciences.) 

 A common species found under deca3'ed wood. It belongs to 

 the same group as P. modicella and P. coy\lorta. 



PiTYS TANEiE, Garr.. pi. 3, fig. 65. 



Shell umbilicate, discoid, thin, snb-pellucid, brownish-horn 

 color, tessellated and rayed with deep-brown, plicately ribbed; 

 ribs small, oblique, arcuatelj' curved, somewhat irregular, rather 

 distant, finer and more crowded beneath ; spire convex, flattened 

 at the apex ; whorls Gi, convex, slowly and regularly increasing, 

 slightly sulcate next the suture, last one acutel}' carinate, flat- 

 tened above, not descending in front, convex beneath, angular at 

 the umbilicus ; suture well impressed ; umbilicus large, perspec- 

 tive, freely showing the whorls, a little more than a third the 

 diameter of the shell ; aperture oblique, rhomboid-lunate, wider 

 than high; parietal region with a small revolving lamella; peris- 

 tome thin, simple. 



Diam. 4^, height H mill. 



Hah. Maupiti I., Society Isles. (Coll. Phil. Acad. Nat. Sciences.) 



A verj' abundant species found on the ground on the sides of 

 wooded hills. It belongs to the same group as P.ficta^fahrefacta.i 

 and Huahinensis. 



PiTYS ZEBRiNA, Garr., pi. 3, fig. 66. 



Shell umbilicate, sub-discoid, thin, pullucid, shining, whitish, 

 corneous, adorned with brown tessellations on the spire, and flexu- 

 ous stripes on the body whorl ; spire depressly convex, apex flat- 

 tened ; whorls 5^, convex, slowly and regularly increasing, last 

 one not descending in front, rounded, obliquely ribbed ; ribs mem- 

 branous, rather distant, interstices under the lens clearl}- elevately 

 striated ; suture deeply impressed ; umbilicus small, pervious, one- 

 sixth the greatest diameter of the shell ; aperture sub-vertical. 



