Our reader Thomas of Baltimore sent these slightly blurry pictures of snails with impressive keeled shells and asked for an identification. He had found them in the Little Gunpowder River north of Baltimore City. I don't normally work with freshwater mollusks and I don't know much about them. But I could see what looked like an operculum on the foot of one of the snails on the left, which indicated they were not pulmonates. At the same time, their looks suggested they were juveniles—often a complicating factor when one is trying to identify a species.
I skimmed thru the pictures in The Freshwater Gastropods of North America to no avail. So I forwarded the pictures to our freshwater expert Rob Dillon. He is a contributor to FWGNA and also writes the blog Freshwater Gastropods of North America.
Rob quickly identified the snails as juvenile Leptoxis carinata, which is indeed an operculated species. It turned out that the adult shells are not keeled (carinated) and therefore look very different than juveniles. Hence my failure to find them among the pictures in FWGNA.