Function. Abstract approved: Signature redacted for privacy.

This is a neuroanatomical and ethological study of the pectines, the primary chemosensory organs of scorpions (Arachnida: Scorpiones). The pectines are paired, ventromedial appendages that brush the substrate as the scorpion walks. This comb-like organ consists of a supportive spine and an array of teeth. Each tooth supports hundreds of setaform sensilla called pegs. The peripheral neuroanatomy of sensilla on the teeth and spine were described. Below the peg sensilla on the pectinal teeth were three histological layers consisting of dendrites, neuronal somata, and a layer of peripheral synapses. The neuronal cell layer within the teeth was further divided into inner and outer sub-larninae, comprised of chemosensory and mechanosensory neurons. The peg sensilla were innervated by iterative cassettes of sensory neurons orthogonal to the layers described. Sensory hairs on the pectinal spine resembled arachnid tactile and chemosensory hairs. The central projection patterns of sensory afferents from tactile hairs on the pectinal spine and peg sensilla on the pectinal teeth were compared. The interna