Watch List notes:

EGYPT, Alexandria. Commodus. AD 177-192. Æ Diobol (22.5mm, 5.35 g, 12h). Dated RY 27 of Marcus Aurelius (AD 186/187). Laureate head right / Agathodaimon serpent erect right, wearing skhent, with a caduceus and grain ear in its coils; L Λ (date) across field. Köln –; Dattari (Savio) 3954 & 9666; K&G 41.128; Emmett 2579.30 (R5). Reddish-brown surfaces with touches of olive green, roughness. VF. Extremely rare, with this coin being the third known specimen. The other two are both originally from the Dattari collection: Dattari 3954 & 9666 (9666 is ex Staffieri Collection–Triton XXI, lot 190–hammer $800).

From the Collection of an English Gentleman.

Keith Emmett also lists this type for Commodus' regnal year 33, and cites a coin in the collection of the American Numismatic Society (1944.100.61909).