Watch List notes:

L. Calpurnius Piso Frugi. Denarius 90, AR 3.96 g. Laureate bust of Apollo l.; below chin, G. Rev. Horseman galloping r., holding whip in upraised r. hand; above, lizard and below, L·PISO·FRVGI / ROMA. Babelon Calpurnia –. Sydenham 657. RBW –. Crawford 340/1.
Of the highest rarity, among the finest of very few specimens known.
Lightly toned and about extremely fine / good very fine

Ex NAC sale 54, 2010, 200.
This L. Piso denarius, unknown to Babelon and Sear, is not a simple variant of the classical type but rather a distinct type in its own right. Infact, classical L. Piso denarii represent the head of Apollo facing left, whilst this type presents the bust in paludamentum in high style and bears a vague resemblance to issues of L. Piso with horse prancing left, hence the reason why we believe them to be the first struck of this magistrate's copious issue.
There are two known varieties of the reverses published by Bahrfeldt NZ 1896, pl. III, 61 with horseman and whip and pl. III, 62 with horseman and palm leaf.
Of the horseman and whip variety we are familiar with the following specimens:
1) Haeberlin 1308, ex. Coll. FONTANA, Paris 1860 n. 84; 2) Haeberlin 1309 sold by HAMBURGER; 3) FFC 344, perhaps even the specimen offered here; 4) Private collection. All from the same pair of dies.
Of the palm leaf type three symbols are known to exist:
Stirrup: 1) Paris 6254; 2) Paris 6255; 3) Turin; 4) Bignami; 5) Gotha; 6) Vidal Quadras y Ramon; 7) Private collection
It is possible that specimens 4, 5 and 6 ended up either in Paris or Turin.
Arrow: 1) FFC 342; 2) Vienna
Anchor: Turin
In conclusion, we know of no more than five specimens of the fantastic whip variety and all are from the same pair of dies whereas of the palm leaf variety, taking into account the three symbols, between six and nine are known to exist. This is undoubtedly one of the greatest rarities of the Republican series. This coin cannot be found at either the British Museum or the American Numismatic Society and has never been offered at a private auction since the sale of Haeberlin in 1933. As for the stirrup, out of respect for learned scholars, we have interpreted thus this symbol, but we would like to humbly point out that this accessory to smoother riding was introduced in Europe only in the VIII. Century AD.