AURICULELLA, OAHU. 97 



until the adult stage is reached, when it diminishes. It differs 

 from A. serrula by the smaller number of whorls in the same 

 length, and by having very few prickles on the parietal la- 

 mella or none at all. 



17. A. TANTALUS Pilsbry & Cooke, n. sp. PI. 24, figs. 15, 16. 



The shell is sinistral, distinctly perforate, but the perfora- 

 tion does not extend deeper than the last whorl; very thin, 

 somewhat glossy, rather distinctly striate; cinnamon-colored 

 (or sometimes with the last two whorls naphthalene yellow), 

 the thin cuticle rather subject to disintegration, producing 

 whitish dots and spots. Apex rather obtuse. "Whorls 6%, the 

 first one convex and glossy, the rest very slightly convex, the 

 last whorl very indistinctly subangular in front of the aper- 

 ture, elsewhere rounded, the base rotund. Aperture of the 

 usual shortly, irregularly-ovate shape, showing the external 

 color within. The peristome is thin, very little expanded 

 outwardly, more at the base ; the columellar margin triangu- 

 larly dilated, not appressed, but projecting forward in an ob- 

 tuse angle, seen in a profile view. Parietal callus very thin. 

 Parietal lamella high and thin. Columella vertical, very in- 

 distinctly biplicate and somewhat excavated below in a front 

 view, but in an oblique view in the mouth the two folds are 

 somewhat more distinct. A fine keel runs vertically on the 

 face of the columella to its base. 



Length 5.9, oblique diam. 2.8 mm. 



Oahu: Pauoa side of Tantalus along the Castle trail (type 

 loc., Cooke & Pilsbry) ; Nuuanu (Cooke). 



This species is closely related to A. tenella Anc., of the 

 Waianae range. It differs from that by having a decidedly 

 larger parietal lamella, a smaller umbilicus and a somewhat 

 different columella, as described above. The little keel or ver- 

 tical rib on the face of the columella is much like that of A. 

 perversa. 



Specimens in the late neanic stage have a strong lamella on 

 the columella, but no palatal fold or callous. 



