Layoff notices are being sent to 155 more District of Columbia employes, officials said yesterday, bringing to 300 the number of workers told their jobs are casualities of the city's prospective $172.4 million budget deficit.

D.C. personnel director Jose Gutierrez said 115 workers in the Department of Corrections -- hardest hit by Mayor Marion Barry's layoff plan -- will be told Friday that they will lose their jobs as of May 22. Notices already have been sent to 110 other corrections employes, many of them prison guards at D.C. Jail and Lorton Reformatory. The Department has 2,049 employes.

Gutierrez also said layoff notices are being sent to 40 employes of the D.C. Department of Recreation, although Barry's original plan to balance the city's budget called for only 12 layoffs in that department.

Recreation Director William H. Runsey said the difference was caused by a recent decision to lay off 28 part-time employes -- such as dance instructors and some lifeguards at the city's swimming pools -- who work only a few hours a week.

This latest batch of layoffs comes at a time there is growing uncertainty over the extent of the layoffs and, in some cases, their legality.

Barry announced March 6 that he would lay off 546 city workers. But last week he said that figure was a "target" made uncertain by the complicated procedure necessary to lay off District employes.

City Council finance commitee chairman John A. Wilson, who has proposed layng off 2,500 workers, met with Barry yesterday but said afterwards that he and the mayor were no closer to an agreement on the number of jobs that must be eliminated.

Wilson's support is crucial to Barry because the mayor's proposed $24 million package of new and increased taxes and user fees must clear Wilson's committee before the council can take final action.

Wilson said several weeks ago that he would begin hearings on the tax package April 24. But yesterday he indicated those hearing might not be held.

"If we hold hearings, we'll discuss two plans, mine and the mayor's," Wilson said.

Organized labor has voiced strong opposition to Barry's proposed layoffs, charging that city workers are being made scapegoats for mismanagement by city officials, the failure of the business community to bear an adequate share of the city's tax burden and the failure of Congress to authorize a sufficient federal payment for the District.

Yesterday,a group of inmates in maximum security facilities at Lorton filed legal action in U.S. District Court here to try to block the corrections department layoffs, charging that reducing the number of guards at the prison would cause "already inadequate" prisoner security to deteriorate.

The inmates said in documents filed with the court that they feared increased violence at the institution as a result of the planned layoffs of guards and administrative staff. So far, no corrections workers actually have left their jobs.

Elimination of 546 city jobs through layoffs and 677 others through attrition by Sept. 30 is key to Barry's budget plan.

Even a delay through court action of the Corrections Department layoffs could throw Barry's plan off course, since the longer it takes actually to remove the workers from the payroll, the less money will be saved.