LAKE TO FOREST OR PRAIRIE 



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

 L. stagnalis; c, L. woodrujfi; d, Physa heterostropha; f, Ancylus fuscus, side view; 

 g, Amnicola cincinnatiensis ; i, A. emarginata; j, Vahata tricar inata; k, Planorbis 

 trivolvis, from above; I, P. trivolvis, side view; m, P. campanulatus, from below; 

 n, P. campanulatus, side view; o, P. bicarinatus, from below; p, P. bicarinatus, 

 side view; q, Vivipera contectoides ; r, operculum of V. contectoides; s, V. subpur- 

 Purea; t, Campeloma ponderosum; u, C. integrum; v, C. subsolidum; w, Pleurocera 

 elevatum; x, P. subulare; y, Goniobasis livescans; z, Sphaerium transversum (a clam). 



