Comparison of shells and animals of Idaholanx n. gen., Fisherola and Lanx. The shells are oriented with the head of the animal facing right, while the whole animals without shells are dorsal views with the head up. Idaholanx fresti sp. n. A shell B whole animal. Fisherola nuttalli: C shell D whole animal. Lanx patelloides. E shell F whole animal. The red arrows indicate the position of the head in A, C; the position of the gap in the columella muscle in B, D and the narrow connection in F. Images not to scale.