16 PRONESOPUPA. 



10. PRONESOPUPA INCERTA n. sp. PL 1, fig. 6. 



The shell is perforate (umbilicus deep, cleft-like), elongate,- 

 subcylindrical, buffy citrine, thin, transparent, the surface 

 silky, shining, minutely, coarsely and evenly costulate. The 

 spire is extended, with slightly convex outlines, the individual 

 whorls convex, separated by a rather deep suture, apex 

 slightly acute. Whorls 5, increasing slowly and regularly, the 

 embryonic, under the microscope, minutely granulose, with 

 costulae beginning at about the middle of the second whorl; 

 the rest of the whorls evenly and regularly costulate ; riblets 

 without membranous edges, on the last whorl about 0.07 mm. 

 apart; the interstices very minutely granulose; last whorl 

 rather large, convex, tapering towards the base, scarcely 

 ascending near the aperture. Aperture toothless, truncate- 

 oval, hardly oblique, nearly perpendicular, the lip -insertions 

 remote, connected by a thin callus. Outer margin of peri- 

 stome slightly thickened, hardly expanded; columellar mar- 

 gin thickened along its edge, arched above the umbilicus, its 

 inner face nearly straight. Length 1.78, diam. 1.02, aperture 

 (diag.) 0.67 mm. 



Kauai: Halemanu (Cooke). Holotype 15467 Bishop Mu- 

 seum. 



As far as known but two specimens of this species have 

 been taken up to the present time. Both specimens were 

 found on the ground on dead leaves, probably shaken from 

 the fronds of ferns. Each came from a different locality near 

 Halemanu. Unfortunately, no immature specimens are at 

 hand to make out clearly the surface structure of the embry- 

 onic whorls, as in both specimens the apices are considerably 

 eroded. The second specimen is lighter in color than the 

 type, with more compact whorls, slightly smaller, with more 

 convex outlines. It has 5 whorls and measures: length 1.71, 

 diam. 1.02, aperture (diag.) 0.64 mm. 



This species is easily recognized from its other relations 

 by its smaller size and slight difference in color. Under a 

 strong lens no spiral striation could be made out in either 

 specimen. At first glance it appears to be closely related to 

 P. admodesta, but is easily separated by its acute and ex- 



