LEPTACHATINA. 3 



smooth, glossy, thin; the last two whorls in- 

 creasing rather rapidly. 



Group of L. obsoleta, species 21-28. 



F. The shells are small, ovate or ovately conic, 

 smooth, pellucid or subpellucid. 



Group of L. accincta, species 29-51. 



G. The shells are slightly larger and thicker than 

 those of F. Group of L. nitida, species, 52-58. 



H. The shells are broadly ovately conic or conic, 

 larger than those of G. 



Group of L. glutinosa, species 59-63. 

 7. The shells are perforate, distinctly striate, 

 narrowly ovate. 



Group of L. semipicta, species 64. 

 J. The shells are striate, broadly ovate-subcylin- 

 drical, nearly solid. 



Group of L. pachystoma, species 65. 

 K. The shells are rather large (for the genus), 

 elongately ovate, nearly solid. 



Group of L. ventulus, species 66-72. 

 L. The shells are rather large (for the genus), 

 snbelliptical, nearly solid. 



Group of L. succincta, species 73-77. 

 M. The shells are umbilicate, with a strong raised 

 callus on the parietal wall. 



Group of L. fossilis, species 78. 

 aa. Surface distinctly costulate or costate. 



N. The shells are small, slender, costulate or 



costate. Group of L. sculpta, species 79-90. 



0. The shells are larger than those of N, glossy, 



costate. Group of L. striatula, species 91-99. 



2. Aperture usually furnished with a denticle or indi- 

 cation of a denticle within the outer lip ; spire slightly 

 concave in outline. 



Subgenus LABIELLA, species 100-103. 



3. Aperture usually furnished (in young shells) with a 

 palatal lamina; shells cylindrical. 



Subgenus PAUAHIA, species 104-106. 



