Englishbred Ben Nevis, ridden by Charlie Fenwick, romped through the Maryland mud to win the 35th running of the Howard County Cup by six lengths over Coney Island today. The only other starter, Rohman Blaze, pulled up after the 17th fence.

"He jumper like a million," said Fenwick, who has handled the liver-colored chestnut gelding in all of its races in this country. "He always stays fit . . . I only get on him about three times a week."

It took a fit horse to negotiage Meriwether Farm's three-mile 20-jump timber course today. The deep going knocked out five of the projected starters, including last year's winning rider, Billy Myers. Myers was scheduled to run Frost Time but was a late scratch. Fortunately for him his nearest rival for the Governor's Cup, Jay Griswold gained only three points with his second place today.

Myers leads with 13 points, with Griswold second with 11. Saturday's Elkridge-harford meeting is the final race in this spring-long series.

Coney Island went to top over the first two jumps but Fenwick took over with Ben Nevis going into the third and was never headed, going across the finish 6:54.

Howard County's solid upright fences are a good test for horses with sight on the Maryland Hunt Cup. Ben Nevis, 8, and with a programmed two years of racing behind him could go that way, joining such legendary jumpers as Blockade and Mountain Drew, which have won here and gone on to win the "Maryland."

Art Willson, who pulled up Roman Blaze in the cup, returned a little later to win the Sharp Mile with Happy Sea. Second was Mr. Emperor, ridden by Jennifer Rowland, who had won the first race of the afternoon on Wine Scandel.