CALLIONEPION. 177 



Key to Genera of Megaspirida. 



I. Apex entire, 2y 2 earliest whorls gramilose; shell with 

 9-10 whorls; columella with a single fold entering the- 

 last whorl; no other internal lamellae. 



Genus Callionepion. 

 II. Apical whorls vertically striate or smoothish. 



1. Spire entire in adults; peristome discontinuous, the 

 ends widely separated; whorls numerous. 



a. Lamellag on the axis and parietal wall pene- 

 trating several whorls, the parietal lamella scal- 

 loped; radial baso-axial nodes developed; no 

 palatal plicae. Genus Megaspira. 



6. Lamellae in the last 1 to 2 whorls only, 3 on the 

 axis ; the parietal lamella not sinuous ; no radial 

 barriers; palatal plicae developed, at least in 

 typical species. Genus Eomegaspira. 



2. Spire truncate in adults; peristome entire, contin- 

 uous, the mouth piriform. 



a. Shell imperf orate, sinistral; aperture without 

 externally visible lamellae; peristome adnate; 

 interior unknown. Genus Perrieria. 



b. Shell umbilicate, dextral, with an entering 

 lamella on the parietal wall, and inside having 

 two axial lamellae and one palatal plica; peri- 

 stome free from the preceding whorl. 



Subgenus Ccelocion. 



Genus CALLIONEPION Pilsbry & Vanatta, 1899. 



Proc. Acad. Nat, Sci. Phila., 1899, p. 371 (Sept. 29, 1899). 



Shell turrited, slowly tapering, with diamond- granulate 

 nepionic shell of about 2y 2 whorls, retained in the adult, the 

 subsequent whorls differently sculptured. Type species with 

 9!/2 moderately convex whorls, apex very obtuse. Aperture 

 ovate, with slightly expanded outer lip, the columellar lip 

 with free expanded edge (as in Bulimulus or Opeas) ; colu- 

 mella with a small, rather sharp oblique median fold, enter- 

 ing the last whorl as a low spiral lamella. Axis slender and 

 nearly straight, perforate throughout. Type C. iheringi. 



