88 LEPTACHATINA, S.-G. THAANUMIA. 



narrower and with slightly more convex outlines. L. semi- 

 picta, from Lanai, is probably related to this species. The 

 latter is slightly larger, more solid and more distinctly 

 costate. 



113. L. THAANUMI n. sp. PI. 6, figs. 16, 17. 



The shell is imperforate, conically ovate, yellowish corn- 

 eous, with a broad reddish brown band at the periphery, 

 thin, subdiaphanous, the embryonic whorls glossy, under a 

 strong lens very faintly spirally striate, the rest finely and 

 closely costulate. Spire subconic, apex obtuse. Suture 

 hardly impressed, faintly margined, crenulate. Whorls 

 barely 6, the first two convex, the rest nearly flat, the last 

 rotundate, slightly tapering towards the base. Apertucre 

 broadly ovate, oblique, nearly perpendicular. Columella 

 nearly straight, slightly twisted, with an almost obsolete 

 oblique fold. Outer margin of lip arcuate, slightly thick- 

 ened within, columellar margin thin, reflexed, adnate. 

 Length 7.7, diam. 3.8, length of ap. 3.4 mm. 



Molokai: Mapulehu ridge (Thaanum). 



L. thaanumi is provisionally located in the subgenus Thaa- 

 numia as the embryonic whorls have the faint spiral sculp- 

 ture on which the separation of the subgenus is almost wholly 

 dependent. This species is, however, imperforate, which char- 

 acter is not found in any other species referred to this sub- 

 genus. It is also narower in proportion to its length than 

 any species of this subgenus, except L. perforata. 



114. L. PERFORATA n. sp. PI. 7, fig. 32. 



The shell is perforate, elongate, attenuate, brown or very 

 dark brown, rather thin, not diaphanous, under a strong 

 lens the embryonic whorls are very minutely spirally striate, 

 the rest costate. Costa? arcuate, regular, 4.6 to the milli- 

 meter, with 45-50 on the last whorl. Spire attenuate, elon- 

 gate, apex somewhat acute. Suture not margined, im- 

 pressed. Whorls 9, slightly convex, the last rotundate, taper- 

 ing towards the base. Aperture perpendicular, slightly ob- 

 lique, shaped like an oblique sector of a circle, acute at both 



