When my sister, Mrs. R. E. GERBRANDS, visited the Riviera di Versilia in Tuscany in 1963, she passed a large reed-land near Marina di Massa. The reed was not the common Phragmites communis Trin. of Central Europe, but the gigantic Arundo Donax L. which can attain 3 m height, has thick stems and very long, broad leaves. Through the reed jungle a narrow path led to a very quiet rivulet, named Fiume Frigido on the map. This rivulet was bordered by dense vegetation and was not visible from the main road. There were no canals, ditches or ponds in the neighbourhood, hence the rivulet was the only locality where freshwater Mollusca could be collected. Among the snails she found was a species reminding one of Planorbarius corneus (L.) by its general shape and convex body whorl, but differing from that species by having the whorls very characteristically keeled above and below, and by its deeply funnel-shaped umbilical region. With the help of Dr. C. O. VAN REGTEREN ALTENA the name of this planorbid could be established as Helisoma anceps (Menke, 1830) = Planorbis bicarinatus Say, 1819 = Planorbis antrosa Conrad, 1834, a North American species. Hereupon I wrote to Mr. H. M. SMITH at Sandusky (Ohio) asking for some American specimens for comparison. He kindly sent me three sets, one from Lake Dunmore (Vermont), one from Lake Erie at Port Clinton (Ohio), and one from Headwater Pond (Ohio). The latter had been collected and identified by Prof. D. H. STANSBERY of Ohio State University. All these shells agree perfectly with my Italian specimens in alle respects.