The Montgomery County chapter of the NAACP has harshly criticized a white political ally on the county Board of Education, saying he made "condescending and patronizing" remarks against blacks during a stormy board meeting last week.

In a letter to the Montgomery Journal that was also released to other publications, NAACP president Roscoe Nix lashed out at James Cronin's comments that the person named to replace Odessa Shannon -- the board's only black member -- should be like her: "quiet" and "tactful."

In the letter, Nix compared Cronin with former South African prime minister Jan Christiaan Smuts. Smuts, Nix said, once told a racially mixed audience that "next to the ass, the Negro is the most patient animal on earth."

Cronin, who many NAACP members worked to elect in 1982, said yesterday in response: "I have to stand on my record." He said he thought nothing productive would come of discussing the letter.

At the Sept. 24 meeting referred to in the letter, the school board elected Jeremiah Floyd, a black educator, to fill a board vacancy left by Shannon, who resigned to become special assistant to County Executive Charles W. Gilchrist.

The meeting began rancorously, with black leaders of several local organizations denouncing the board for its decision to hold the election at the end of the evening. They contended that it was an attempt to thin the crowd most interested in the decision.

One black leader accused the board of acting like the Ku Klux Klan and another said he would have challenged board president Marilyn Praisner to a fight if she were a man for her "disrespectful" reaction to his comments.

Responding that night, Cronin called the criticism "intemperate" and said it amounted to "bullying." He chastized the NAACP for not repudiating individuals in the organization who had been quoted in press accounts as calling two black candidates for the seat "Oreos."

While being "quiet" and "tactful" "are laudable characteristics in any person," the NAACP letter said, "to insist that they be typical of blacks, in this context, is to place Dr. Jeremiah Floyd and all blacks in an accommodationist straightjacket.

"Dr. Cronin's words communicate to all of us who spoke at the that evening that if he does not believe Smuts' words to be true, he believes that they ought to be true in Montgomery County."