thoracic limb n.
See upper extremity.
In the Cumacea and Tanaidacea only the first thoracic limb has a branchial epipodite.
A single bone, the humerus, forms the skeleton of this portion of the thoracic limb.
In Apus, as the figure shows, there are four of these “antenna-like” palps or filaments on the first thoracic limb.