84 LEPTACHATINA, S.-G. THAANUMIA. 



Oahu: Waianae Mts. (Baldwin). 



Thaanumia omphalodes ANCEY, Proc. Malac. Soc. London, 

 iii, 1899, p. 269, pi. 12, fig. 8. 



This species is the type of the sub genus Thaanumia. 



The comparatively large and open umbilicus easily separ- 

 ates this from the other species of the subgenus. 



108. L. OPTABILIS n. sp. PI. 13, fig. 9. 



The shell is minutely but distinctly perforate, ovate, light 

 corneous with a broad brown band above the periphery, rather 

 thin, silky, minutely and closely striate, with more distinct 

 striae on the neanic whorls and just below the suture of the 

 last whorl, under a very strong lens the embryonic whorls 

 are indistinctly spirally striate. Spire almost conic with 

 slightly convex outlines, apex rather blunt. Suture im- 

 pressed, not margined, rather deep and very distinct on the 

 embryonic whorls. Whorls 5%, the embryonic indistinctly 

 shouldered, the rest slightly convex, the last subcylindrical, 

 tapering towards the base. Aperture ovately pyriform, 

 hardly oblique, very slightly diagonal. Columella slightly 

 oblique, narrowly triangular, with a rather strong sub-basal 

 fold. Outer lip regularly curved, convex, slightly thickened, 

 columellar margin thin, adnate above, reflexed over the min- 

 ute umbilicus. Umbilicus minute. Length 6.8, diam. 3.6 

 mm. Length of ap. 3.3 mm. (Cooke). 



Oahu: Waianae Mts., back of Leilehua (Cooke). 



There is a unicolorous light brown variety of this species 

 from the same locality. This species was found in rather 

 open and dry country. The spirally striate embryonic whorls 

 and the presence of a perforation places this species in the 

 subgenus Thaanumia. It differs from L. omphalodes Anc. in 

 having a less open umbilicus and the surface is not as dis- 

 tinctly costate. The peculiar silky luster is present in both 

 species. 



109. L. FUSCULA (Gulick). PL 3, fig. 51. 



"Shell dextral, imperf orate, ovate conic, thin, with but 

 little polish, of a brown succineous color, and very finely 



