The coxal gland is a gland found in some arthropods, for collecting and excreting urine. They are found in all arachnids (with the exception of some Acari), and in other chelicerates, such as horseshoe crabs.[1] The coxal gland is thought to be homologous with the antennal gland of crustaceans. The gland consists of an end sac (saccule), a long duct (labyrinth) and a terminal bladder (reservoir).[2] There is generally only one pair (two in some spiders), and they open on the coxae of the walking legs[1] or at the base of the second antennae in the case of the crustacean antennal gland.[3]: 70–71 The coxal secretion of adult female ticks of Ornithodoros erraticus contains a sex pheromone.[4]