1871.] MR. HARPER PEASE ON POLYNESIAN LAND-SHELLS. -153 



To the above genus I add the following new species : — 



PlTYS ATIENSIS, Pse. 



T. orbicularis, tenuiuscula, aperte umbilicata, radiatim conferte et 

 subarcuatim costulata, supra et infra flavido et rufo tessellato- 

 strigata ; spira vix elevata, apice obtuso, sutura bene impressa ; 

 anfr. 5, convexi, ultimus ad peripheriam basinque rotundalus ; 

 apertura subcircularis , obliqua ; perist. simplex, rectum. 

 Diam. 3, alt. 1| mill. 

 Hab. Insula Atiu. 



P. modicella (Fer.) is the nearest allied species, from which it 

 differs in being more openly umbilicate, the spire more elevated, and 

 the colours differently disposed. 



PlTYS ROTELLINA, Pse. 



T. planorboidea, solidiuscula, anguste umbilicata, tenuissime radiatim 

 striatula, supra planiuscula, vix elevata, apice depresso : anfr. 6, 

 plano-convexi, ultimus ad peripheriam basinque rotundutus ; aper- 

 tura obliqua, lunaris, subcompressa, angusta; paries aperturalis 

 lamella unica intrante munitus ; perist. simplex, rectum ; flavido 

 et rufo ulternatim undique strigata. 



Alt. 1, diam. 2 mill. 



Hab. Insula Aitutake. 



PlTYS IMPERFORATA, Pse. 



T. imperforata, vel punctiformi-perforata, orbicularis, tenuiuscula, 

 radiatim confertim et tenuissime costulata, flavido et rufo radiatim 

 tessellato-strigata, strigis ad peripheriam basinque flcvuosis ; 

 spira plano-convexa, apice obtuso, sutura impressa; anfr. 6, 

 plano-convexi, strictim et lente accrescentes, fere cequaliter, ulti- 

 mus ad peripheriam rotundatus, basin plano-convexus ; apertura 

 obliqua, lunaris, lamellis 4—5 munita, 2 in pariete aperturali, 2—3 

 in margine basali ; perist. simplex ; columella callosa, vix eversa. 



Diam 4, alt. 2 mill. 



Hab. Insula Aitutake. 



Nearest allied to P. rotula, Jacq. It has more whorls, is dis- 

 tinctly radiately ribbed, and the reddish stripes extend over the base 

 in zigzag shape. 



PlTYS RORATONGENSIS, Pse. 



T. orbicularis, tenuiuscula, nitidiuscula, aperte umbilicata, radiatim 

 conferte subflexuoso- costulata, flavido et rufo radiatim alter natim 

 strigata, strigis ad peripheriam basinque undulatis ; spira vix 

 elevata, apice depresso, sutura bene impressa ; anfr. 4£, rotundato- 

 convexi, leviter accrescentes, ultimus ad peripheriam basinque 

 rotundatus; apertura obliqua, lunaris, lamellis 4 munita, 2 in 

 pariete aperturali, 2 dentiformibus in tnargine basali ; peristoma 

 columellaque simplicia. 



Diam. 2\, alt. 1 mill. 



Hab. Insula Roratonga. 



