TAB. XV. 



Fig. 



1. Planorbis obtusus. No. 53, p. 102. 



a. View of the upper disc (distorted specimen). 



b. Side view. 



c. Ditto (distorted specimen). 



d. View of the under disc. 



e. View of the upper disc. 



2. Planorbis platy stoma. No. 56, jo. 103. 



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



b. View of the under disc, magnified. 



c. View of the upper disc ditto. 



d. View of the aperture ditto. 



3. Planorbis oligyratus. No. 55, p. 103. 



a, b. Views of the aperture. 



c. View of the under disc. 



d. View of the upper disc. 



e. View of the under disc of a cast. 



4. Planorbis rotundatus. No. 52, p. 100. 



a. Side view showing the aperture. 



b. View of the under disc. 



c. View of the upper disc. 



5. Planorbis euomphalus. No. 51, p. 99. 



a. View of the upper disc. Young shell. 



b. Ditto ditto ditto. 



c. Side view, showing the aperture in ditto. 



d. View of the under disc of ditto. 



6. Planorbis euomphalus. No. 51, p. 99. 



a. Side view of adult shell. 



b. View of the under disc of ditto. 



c. View of the upper disc of ditto. 



7. Planorbis discus. No. 54, p. 102. 



a. View of the upper disc, with the shell preserved (intermediate 



stage of growth). 



b. View of the under disc of a cast. 



c. Side view of a cast. 



d. View of the upper disc of a cast. 



