EXPLANATION OF PLATE XXXII. 
Figure l. LIMN4A PALUSTRIS Miiller. 
2. LIMN4A PALUSTRIS EXPANSA Lea. (SUFFLATUS Calkins). 
3. LIMN4A REFLEXA EXILIS Lea. 
4. LIMN4A REFLEXA JOLIETENSIS Baker. 
5. LIMN4A PALUSTRIS MICHIGANENSIS Walker. Large va- 
riety. 
6. LIMN4A REFLEXA Say. 
7. PLANORBIS TRIVOLVIS Say. Age variation. 
8. PLANORBIS TRIVOLVIS Say. 
9. PLANORBIS TRIVOLVIS Say. 
10. PLANORBIS TRIVOLVIS Say. (DiIsSTORTUs Calkins). 
11. PLANORBIS CAMPANULATUS Say. 
12. PLANORBIS BICARINATUS Say. 
15. PHysaA sAyII Tappan. Short spired variety. 
14, VALVATA TRICARINATA Say. Enlarged. 
15, VALVATA SINCERA Say. Enlarged. 
16. APLEXA HYPNORUM Linné, 
All figures natural diameter except where otherwise mentioned. 
