OP CONCHOLOGY. 291 



5. Helix decussatula, Pease. 



Descnptum. — T. discoidea, depressa, umbilicata, fusco-casta- 

 nea et fulvo-maculose strigata, obliqu4 confertim et arcuatini 

 costata, costellis volventibus decussata ; anfr. 4-5, convexo- 

 rotundatis, setigeris ornatis ; sutura impressa, spira parurn 

 elevata ; ad peripheriam rotundatim obsolete angulato ; um- 

 bilico J diametri subrequante ; apertura elliptica, vix obliqua, 

 lamella unica intro volvente instructa. 



Dimensions. — Diam. 4|, alt. 2| mill. 



Sbell discoidal, depressed, umbilicate, obliquely ribbed, ribs 

 close, small, and somewhat curved or flexuous, decussated by 

 concentric rib-striae, which are more numerous and conspicu- 

 ous on the base ; whorls 4-5, convexly rounded, and sparsely 

 ornamented with short hairs; suture impressed, spire but 

 slightly elevated ; periphery rounded or obtusely angulated; 

 umbilicus about one-third the diameter of the shell, rounded 

 on its edge ; aperture somewhat oblique, and roundly ellipti- 

 cal, furnished with a single prominent lamella on the penulti- 

 mate whorl ; the radiating ribs of the exterior extend within 

 the aperture. Mottled and striped irregularly with chestnut- 

 brown and pale yellow. 



Habitat. — Sandwich Islands. 



6. Helix rugata. Pease. 



Description. — T. lenticulari, umbilicata, obliqu^ et irregu- 

 lariter rugosula striata, et striis spiralibus decussata ; anfr. 5, 

 tumidiusculis, ad peripheriam acute carinato, spira parum ele-- 

 vata, apice obtuso, basi convexiusculo, ad umbilicum rotu^nde 

 angulato ; umbilico ^ diametri subasquante ; apertura sub- 

 rhomboidea, lamellis duabus conspicuis parietalibus,, unica 

 parva in supero, dentibus lamellasformis tribus in labium. 

 Fusco et pallid^ fulvo tessellata. 



Dimensions. — Diam. 5, alt. 2 mill. 



Shell lenticular, umbilicate, irregularly ribbed obliquely; 

 ribs small, wrinkled or flexuous, and decussated by concen- 

 tric striae ; base decussated by revolving and radiating rib- 

 striae ; whorls 4-5, slightly swollen, sharply carinate at pe- 

 riphery ; spire but slightly elevated ; apex obtuse ; base some- 

 what obversely conical, plano-convex; umbilicus about one- 

 third the diameter of the shell, roundly angulate on its edge; 

 aperture subrhomboidal, furnished with two prominent lamel- 

 lae on the penultimate whorl, a small one on the upper side, 

 and three lamelliform teeth on the labrum and pillar. 



Habitat. — Sandwich Islands. 



