LAKE TO FOREST OR PRAIRIE 



2 33 



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

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

 g, Amnicola cincinnatiensis ; i, A. emarginata; j, Valvata tricarinata; k, Planorbis 

 triwlms, from above; /, 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. snbpur- 

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

 elevatum; x,P.subulare; y, Goniobasis livescens; z, Sphaerium transfer sum (a clam). 



