68 LEPTACHATINA, GROUP N. 



sutural band. A few specimens also vary in having an al- 

 most smooth surface. 



89. L. TENUICOSTATA Pease. PL 1, figs. 10, 11. 



" Shell thin, dextral imperforate : elongately ovate, longi- 

 tudinally plicately costate, golden; whorls 5, convex; suture 

 well impressed; columellar fold white, small, oblique; lip 

 slightly thickened. Length 7.5, diam. 3.5 mm." (Pease.) 



Hawaii: Mana fossil (Henshaw, Thaanum). 



Leptachatina tenuicostata PEASE, Journ. de Conchyl., 1869, 

 p. 170. Achatinella (Leptachatina) tenuicostata PFR., Mon. 

 Hel. Viv., viii, p. 250. Leptachatina tenuicostata SYKES, 

 Fauna Haw., ii, 1900, p. 371. ANCEY, Journ. Malac. xi, 1904, 

 p. 69. 



I have been unable to find a single authentic specimen of 

 this species. It is not represented in the Pease collection in 

 Cambridge. Only a few shells from the Mana deposits seem 

 referable to this species. They may be related to L. (Thaa- 

 numia) henshawi Sykes, for in the fossil material all trace 

 of the spiral lines on the embryonic whorls might have been 

 lost. As the shells are imperforate it is probably better to 

 leave the species in Leptachatina s.s. In the fossil material, 

 the columella is nearly straight, with an acute longitudinal 

 thickening along its face; the columellar fold is very deeply 

 seated and oblique; the aperture is narrow, acute at both 

 ends ; there are 6-6y 2 whorls. An average specimen measures : 

 length 8.0, diam. 3.8, length of ap. 3.7 mm. A Mana shell is 

 figured, figs. 10, 11. 



90. L. IMITATRIX Sykes. PI. 1, fig. 14. 



"Shell elongate, turrited, imperforate, dextral, somewhat 

 thin, yellowish corneous, under a lens minutely longitudin- 

 ally striate; whorls 6%, flatly convex, the last equal to 4/7 

 the length of the shell ; suture impressed ; aperture elongately 

 oval, with the dextral margin arcuate, acute, columellar mar- 

 gin slightly thickened, reflexed, furnished with a very small, 

 inconspicuous fold, the margins united by a thin callus. 

 Length 7.0, diam. 2.6 mm." (SyJces.) 



