CURVELLA, WEST AFRICA. 47 



what arbitrary, and the boundaries of the two groups in de- 

 tail are still unsettled. 



The species were considered Bulimi in the older classifica- 

 tions, but there is no doubt that they are Achatinoid. 



Reproduction is by globular eggs, small and calcareous- 

 shelled, as in the closely related group Opeas. 

 The species may be grouped thus : 

 African species: 



West Africa, species 1 to 10. 

 East Africa, species 11 to 20. 

 South Africa, species 21 to 28. 

 Indian and Chinese species, no. 29 to 37. 

 East Indian and Philippine species, no. 38 to 45. 



Key to West African species of Curvella. 



I. Axis perforate. 



a. Aperture half the length of shell or more. 

 b. Length 5.5, diam. 2.5 mm., whorls 6. 



C. ovata, no. 7. 

 bb. Length 12 mm. 



C. guineensis, no. 9 ; C. concentrica, no. 8. 

 aa. Aperture decidedly less than half the length. 



C. terrulenta, no. 10 ; C. redfieldi juv., no. 3. 

 II. Axis imperforate in adult shells : 



a. Columella straight or nearly so. 



b. Sculpture of growth-striae; 5 convex whorls; 



length about 10 mm. C. inornata, no. 6. 



bb. Sculpture of growth-striae and spaced 



grooves; whorls 5%; 9x4, aperture 4.5 mm. 



C. liberiana, no. 5. 

 aa. Columella decidedly sinuous. 



b. Aperture less than half the total length; 



sculpture of striae or growth- wrinkles only. 



c. Length 11, diam. 4.7, apert. 5 mm.; 



6% whorls. C. decepta, no. 4. 



cc. Length 10.7-11, diam. 3.5-4, apert. 4- 



4.3 mm. ; 7 whorls. C. redfieldi, no. 3. 



