LAKE TO FOREST OR PRAIRIE 



233 



Fig. 324. — Water snails showing generic characters: a, Lymnaea reflexa; b, 

 L.stagnalis; c, L.woodruffi,; d, Physa heteroslropha; f, Ancyliis fitscus, side view; 

 g, Amnicola cincinnaticnsis; i, A. emarginata; j, Valvala tricar inata; k, Plauorbis 

 trivolvic, from above; /, P. trivolvis, side view; m, P. campanulatns, from below; 

 n, P. campanulatns, side view; 0, P. hicarinatus, from below; />, P. bicarinalus, 

 side view; q, Vivipera contectoides; r, operculum of V. contccloidcs; s, V. sub pur- 

 purea; t, Campeloma ponderosum; u, C. integrum; v, C. subsolidum; w, Pleuroccra 

 elevatimi; x,P.subtdare; y, Goniobasis livesccns; z, Sphacrium transversum (a. clam). 



