Fairfax County police said yesterday they have made their first arrests in connection with the "Butch and Sundance" robberies of a series of Northern Virginia pharmacies during the last four months.

Arrested over the weekend were Terry Lee Snow, 30, who police said had no fixed address, and Calvin Hewitt Fulmer II, 28, of 2839 Marshall St., Falls Church. Police identified both as unemployed.

Police said a "substantial" amount of narcotics also was confiscated Sunday.

The men were charged with the July 19 robbery of the Boulevard Medical Center at 8301 Arlington Blvd., during which about $600 in drugs and cash were taken. Snow also is charged with the robbery Aug. 7 of the Apothecary of Burke at 8996 Burke Lake Rd. in Fairfax County.

The robberies were among a total of 11 holdups at Northern Virginia drug stores since April. According to police, the methods used by the armed assailants in each case were similar.

Police said yesterday they still are seeking at least one suspect in connection with the robberies. "We have no idea of the number of arrests that will eventually be made," said a police spokesman.

At last count, the series of robberies included six in Fairfax County, two in Alexandria, two in Arlington and one in Prince William County.

Two other robberies in May and June in Prince George's County, originally thought to be unrelated, may be added to that total, a Prince George's police spokesman said yesterday.

Fairfax police said Snow was arrested at 4:15 a.m. Saturday as he drove through the intersection of Littleton Street and Elizabeth Lane, near Rte. 236. Fulmer was arrested at 6 p.m. Sunday at a house on Walker Street in Annandale.

Snow, who was in custody yesterday at the Fairfax jail in lieu of $150,000 bond, is charged with two counts of armed robgery, use of a firearm in the commission of a felony, and three counts of possession of controlled drugs with intent to distribute.

While the total figure for stolen goods in the robberies did not exceed $7,000, James Sizemore of the Fairfax police pharmaceutical control unit said a 20-cent tablet of Dilaudid, a morphine-based drug demanded during the robberies, could satisfy a heroin addict for four hours. Sizemore said one tablet "could sell for $20 on the street."

Fulmer is charged with one count of armed robbery and is in the Fairfax jail in lieu of $10,000 bond.

A perliminary hearing for both is set for Sept.

Witnesses said each robbery was performed by one white and one black suspect. Both Snow and Fulmer are white.

Whoever robbed the stores "specialized in hitting smaller, independent pharmacies where customers were fewer and security was almost nonexistent. In each case, they would choose a pharmacy that was on a main thoroughfare to effect a speedy escape," Fairfax police spokesman Warren Carmichael said.

Several victims called the robbers "professional and calm." One specifically requested morphine-based drugs, while the second ordered another worker to empty each pharmacy's safe and cash register, witnesses told police.