Complex sentence: 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.
Split into simpler sentences: Orthalicidae (orthalicid land snails) are a family of tropical pulmonate air-breathing land snails. These terrestrial gastropod mollusks are classified in the informal group Sigmurethra of the clade Stylommatophora.