Don't bother rushing upstairs to look in that pile of castoff change lying on your bureau for any examples of this rarer- than-rare coinage. It's not going to happen.

These extraordinary coins, part of the estate of Mary Fane Fry, are the second oldest to be produced in America, the first being in Massachusetts in 1652. The coins are also the first circulated in America that portray the image of an individual.

Known collectively as the Baltimore sixpences, they are the first true portrait coinage to appear in America, and bear the image of Cecil Calvert, the second Lord Baltimore.

In July, the coins were discovered at Fulbeck Hall in Lincolnshire, the ancestral seat of the Fane family, in a cylindrical silver counter box, circa 1680, with the initials "I.C." within a heart, and the base engraved with the larger initials of "M.B."

"It is known that the coins have been at Fulbeck for several generations, and quite possibly since the 17th century, although no firm provenance details linking them to an individual member of the family has been established so far," said a description written by James Morton and Steven Lloyd in the Morton & Eden auction catalog.

"Similarly, the identity of 'M.B.,' whose initials are engraved on the box, remains a matter for speculation. Research into Fane, Calvert and Brent families has yielded a number of possible connections and coincidences but not, as yet, any firm evidence."

"It was an amazing discovery and [they] were found in a cardboard box with other effects of Mrs. Fry," said James Morton in a telephone interview from London the other day. "They were used over the years as counters or markers for card games played at home."

"I've been very fortunate in my career and have had many interesting discoveries, but what is so amazing about this one is that all of the sixpences were found in one place," he said.

"There are probably somewhere between 50 and 100 known specimens and this increases the population by 25 percent," Morton said.

Cecil Calvert was presented a land grant in 1632 of about 10 million acres in what is today's Maryland by England's Charles I. The land was named for Queen Henrietta Maria, the wife of Charles I.

The charter granted Calvert "all Royal Jurisdictions and Perogatives, both Military and Civil ... as Power to Enact Laws, Power of pardoning all manner of Offence, Power to confer Honors &c."

At the time, tobacco was the new colony's form of currency, with gunpowder and musket balls as change.

"The system broke down over time as tobacco production increased and inflation soared. Trade suffered and this, together with a local rebellion, territorial claims by Virginia and accusations by radical elements in England persuaded Calvert to provide a silver coinage for the colony," according to the auction catalog.

While issuing coinage was not expressly granted in the charter, Calvert felt it was within his right to do so. Also, the new coins bearing his likeness would be a "bold decision which would help assert his authority," wrote Morton and Lloyd.

They would be struck to exacting standards of English silver but at a different weight standard to take into account the fluctuating and different exchange rates found in the colonies.

Officials at Morton & Eden explained that it is uncertain who in London engraved the dies or struck the coins, but it's quite possible that it was the Tower Mint.

"The Tower Mint, with its satellite workshops and competing factions of traditional moneyers and machine- coiners, was in a bitterly divided, parlous, unhappy state by 1658, and a commision such as Calvert's would surely have been welcomed by any part of it," said the catalog.

Auction officials said the appearance of the coins with somewhat ragged edges and uneven striking has much in "common with English silver of the time although the individual weight standard, on the evidence of the surviving specimens, was very inconsistent."

"The legends of the coins "emphasize Calvert's sovereignty as 'Lord' (Dominus) of 'Mary's Land,' whilst the heraldic crown used above his family arms stretches the point to say the least," wrote Morton and Lloyd.

The legend Crescite et Multiplicamini also appears on the coins. Crescentia was the proposed named of Calvert's colony before Mary's Land was substituted.

"The legend was neither a motto of the Calvert family, nor ever of Maryland itself, although it was to reappear on several issues of State paper money in the 18th century and on other official documents," wrote Morton and Lloyd. Initial samples were sent to Philip Calvert, Cecil's brother in Maryland, for approval by the colony's governor and council, with the main shipment arriving between 1661 and 1662. A law was passed requiring each "householder" and "freeman" in Maryland to exchange 60 pounds of tobacco for 10 shillings of the new coin.

"Certainly the coins were not welcomed as Calvert had hoped (and as was required under his charter) and relatively few examples survive," wrote Morton and Lloyd.

"By the end of the century they seemed to have dropped out of circulation entirely, and in 1706 a law was passed stipulating that payments should henceforth be made in legally valued crops," they wrote.

A highly interested crowd of buyers assembled in London Wednesday and Thursday for the auction. Total sales for the sixpences, excluding the silver cylinder, was $228,679.

One of the rarer pieces was the Lord Baltimore sixpence with Crescentia misspelled, one of three known to have this error. New York coin dealer Larry Stacks bought it for $52,356.

"The coin was probably from an early obverse die which was later corrected,"" said Morton.

Several of the coins were bought by collectors. Morton thought most of the coins would be returned to the United States.

"Their discovery was like a time capsule and because they were unrecorded, that added greatly to their appeal," he said.