Neptune with a Hippocamp

Neptune stands on a plinth with truncated corners to the right of the recumbent hippocamp, resting his right foot on the creature's hind leg and his left foot on its tail. His head is turned to the left, gesturing; his left hand is raised (holding a missing trident), while in his right hand he holds a fold of his mantle before him. The mantle falls from his left shoulder and upper arm to the floor, largely covering his back. The hippocamp, with its mouth open, lies beside him on the floor with its forelegs bent.