Michael P. Gleason, Prince William County public relations director, casually thumbed through a new county telephone directory last week and then did a double take.

"It looked like someone had taken a 1950-vintage county phone book, thrown it into a blender, then slapped the numbers in a new book," he said. "Phone numbers for some county departments are listed under other departments and so on."

But what worries Prince William officials most is that the new phone book, published by a Kansas company, lists 911 as an emergency police number on the inside cover. The County Police Department does not use the 911 emergency phone system and has no plans to do so, said Lt. Ernest Grove, a department spokesman.

"If they call 911, they aren't going to get the police," Grove said. "They will get a fire dispatcher who will then have to call the police, creating quite a delay."

Mast Advertising and Publishing Inc. of Kansas City, Kan., has apologized to the county. It plans to run advertisements in a local newspaper next week warning of the error.

"We're not trying to excuse the 911 error," Ed Guffey, vice president of suburban sales, said in a telephone interview last week. "But as in any directory, things change."

He said Mast employes based in Prince William called the county government last year for a listing of telephone numbers.

"Obviously, there was some miscommunication," he said.

Guffey said Mast publishes more than 500 phone directories nationwide, although this is the first year it has produced the Prince William book.

The new directory has a map of the county on the cover. Inside, the front page lists government numbers, followed by white pages including business listings and the yellow pages. It was distributed last week to about 130,000 county homes.

The new directory has many numbers for county offices wrongly listed. For example, the Community Mental Health Center is listed as the main phone number for all county offices.

Peggy Bertram, director of the center, said her office has not been receiving calls from people seeking the county government. But, she said, she is aware of the mix-up and expects some calls in the future.