74 AURICULELLA, OAHU. 



c 1 . Outer lip blunt but not duplicate ; perforate or 



umbilicate. 

 d. Rather small, less than 9 mm. long. 



e. Diameter half the length; uniform yel- 

 low, thin. straminea, no. 2. 

 e 1 . Diameter more than half the length ; yel- 

 low or variegated. auricula, no. 3. 

 d 1 . Larger, usually over 10 mm. long; solid, 



opaque. 



e. Yellow, nearly uniform or with a cinna- 

 mon spire ; distinctly striate. 



olivacea, no. 5. 



e 1 . Yellow with brown band, amoena, no. 4. 

 e 2 . Last whorl opaque white or marked with 

 brown. montana, no. 6. 



a 1 . Columella edentulous or having an obtuse median fold ; 

 whorls of the spire strongly convex ; length 4 to 5 

 mm., with 5 to 6 whorls. GROUP OF A. PERPUSILLA. 

 &. Shell sinistral. 



c. Broadly ovate, veiitricose, length 4.5 mm. 



perversa, no. 11. 



c 1 . Ovate, smaller, length 4 mm. perpusilla, no. 12. 

 6 1 . Shell dextral. minuta, no. 10. 



II. Form high, the length twice or more than twice the ob- 

 lique diameter ; shell and lip thin ; columella biplicate, 

 at least in the immature stages. GROUP OF A. CASTANEA. 

 a. Shell perforate or umbilicate. 



b. Shell dextral ; length 8 mm. chamissoi, no. 18. 



& 1 . Shell sinistral. 



c. Cinnamon with paler streaks, 8 to 9 mm. long, 

 with 8!/2 whorls. tenuis, no. 19. 



d. Length about 6 mm., with Qy 2 to 7 whorls. 

 e. Parietal lamella small; umbilicus moder- 

 ate; Waianae Mts. tenella, no. 20. 

 c 1 . Parietal lamella well developed, perfora- 

 tion small ; eastern. tantalus, no. 17. 

 d 1 . Shell imperforate, the columellar margin appressed. 



