CIMRM Supplement - Tauroctony sold at Christies in London in 2012.
Note the bull's tail turning into a wheatsheaf.
Christie's catalogue entry.
Sale 4925, Lot 322. Sold for £79,250 ($128,227) in London 26 April 2012. Previously in a Swiss collection. Previous to that owned by Antiquarium Ltd, New York, in 1993-4. Published by Antiquarium Ltd., New York, 1992 (Myth and Majesty, no. 30).
Site states: "A Roman marble group of Mithras Tauroctonous. Ca. 2nd century. This god shown dispatching the bull, wearing a Phrygian cap, a tunic, close-fitting trousers, and a chlamys billowing out behind, pulling the head of the bull back with his left hand, stabbing its shoulder with a dagger in his right hand, a snake and hound rear up lapping the blood from the wound, a scorpion below biting the bull's pendulous testicles, on an integral plinth 14.25 in. (37 cm.) long."