ovigers

— The third appendage is modified in some pycnogonids and xiphosurids for use in reproduction, as either an ancillary pair of claspers or ovigers (Fig. 26a, b ), and this appendage is differentiated into a tactile sensory limb (Fig. 26f ) in some arachnids, including thelyphonids, while some opilionids have a differentiated fourth appendage.