8. Planorbis lens. No. 57, p. 104. 



a. View of the upper disc, nat. size. 



b. Side view, magnified. 



c. View of the under disc, ditto. 



d. View of the upper disc, ditto. 



9. Planorbis Sowerbyi. No. 62, p. 108. 



a. View of the upper disc of a cast, nat. size. 



b. Ditto ditto magnified. 



c. Side view of ditto, showing the aperture, ditto. 



d. View of the under disc of ditto, magnified. 



10. Planorbis tropis. No. 58, p. 106. 



a. View of the under disc, nat. size. 



b. Ditto ditto magnified. 



c. Side view of ditto ditto. 



d. View of the upper disc ditto. 



11. Planorbis hemistoma. No. 59, p. 106. 



a. View of the under disc, nat. size. 



b. Ditto ditto magnified. 



c. Side view of ditto ditto. 



d. View of the upper disc ditto. 



12. Planorbis elegans. No. 60, p. 107. 



a. View of the under disc, nat. size. 



b. Ditto ditto magnified. 



c. Side view of ditto ditto. 



d. View of the upper disc ditto. 



13. Planorbis biangulatus. No. 61, p. 108. 



a. View of the upper disc, nat. size. 



b. Side view of ditto magnified. 



c. View of the under disc ditto. 



d. View of the upper disc ditto. 



