Orthalicidae (orthalicid land snails) are a family of tropical air-breathing land snails, terrestrial pulmonate gastropod mollusks are classified in the informal group Sigmurethra of the clade Stylommatophora. They are medium-sized to large snails, from about 3 cm (about 1.2 inches) to 9 cm (about 3.5 inches) in shell length.