Top--Line drawings of coiled marine gastropods from the middle Permian Arcturus Formation, White Pine County, Nevada, assigned to the genus-species Straparollus (Leptomphalus) arcturus. Photograph courtesy Thomas E Yancey; I edited and processed the image with photoshop.

Bottom--Line drawings of bellerophon marine gastropods from the middle Permian Arcturus Formation, White Pine County, Nevada, assigned to the genus-species Euphemitopsis subpapillosa. Photograph courtesy Thomas E Yancey; I edited and processed the image with photoshop.