The Interior Department, facing mounting pressure, yestesday rescinded the firing of a scientist who protested the offering of rattlesnake meat at one of Interior Secretary Cecil D. Andrus' favorite Washington restaurants.

The proposed firing of endangered species herpetologist C. Kenneth Dodd "did not fit the offense," Assistant Interior Secretary Robert L. Herbst said yesterday.

Specifically, the "offense" was writing a letter to Dominique's on U.S. Fish and Wildlife Service statonery telling the owner of the French restaurant that the snake in question was in danger of becoming extinct, and asking "respectfully" that it be taken from the menu.

While he described Dodd as a "useful employe" who has "suffered enough," Herbst suggested that a letter of admonition would be sent to the GS-12 biologist.

"I feel relieved and glad to have my job back," Dodd said last night. After receiving notice of his dismissal, Dodd had conceded he might have been overzealous, but he contended that dismissal was an excessive penalty.

A coalition of 15 national wildlife groups agreed. They wrote Andrus last week demanding Dodd's reinstatement. Several members of Congress also supported the $21,000-a-year scientist.

Dodd was handed the letter of reinstatement at 4:15 p.m. yesterday by Endangered Species Program Director Hal O'Conner, who drove across town to deliver the sealed envelope personally to Dodd in the department's Arlington office.

"I've been asked to give this to you," O'Conner said, handing over the letter and heading immediately for the door, according to Dodd.

A stunned Dodd was about to leave work when he read the letter, walked down the hall and told the first coworker he saw, "I got my job back." A botanist who drives in Dodd's car pool invited him over for a drink to celebrate, he said.

Although a perturbed Andrus told reporters Saturday that he expected the controversy about the firing would "blow over" in four or five days, pressure to reverse the decision had been mounting in recent days on Capitol Hill.

Herbst would normally have reviewed the proposed firing of Dodd, but the assistant secretary's entry into the matter yesterday came well ahead of schedule, an Interior spokesman acknowledged.

"We've received a lot of communications from Congress and the public," the spokesman said. "A very considerable number have" opposed Dodd's firing.

"This is not to say we did it because of the pressure," the spokesman added quickly, referring to the reinstatement.

The day before Yesterday's sudden action by Interior, several members of Congress said they had put Andrus on notice either to reinstate the 29-year-old Dodd at once or face a possible House inquiry into the matter.

"Offending the owner of your boss' favorite restaurant is hardly cause for dismissing a civil servant," said Rep. Patricia Schroeder, (D-Colo.), chairwoman of the House Civil Service subcommittee.

She warned that unless the firing was rescinded, she would hold hearings to look into possible violations of the Civil Service Reform Act.

"We just tried to make the heat go as high as we know how," said Rep. John D. Dingell (D-Mich.). A conservationist, he is the author of the Endangered Species Act.

Even Dodd's reinstatement did not mollify Dingell, who said he questioned whether Dodd should receive a reprimand of any sort.

"His case is not closed," Dingell said. He called Herbst's decision to admonish Dodd for writing the restaurant owner "totally unacceptable" and demanded that Andrus personally apologize to Dodd for "subjecting him to public embarrassment."

Andrus could not be reached for comment last night, and his role in the firing and rehiring remained unclear. Asked if he had any personal knowledge that Andrus ordered Dodd fired in the first place, spokesman Chris Carlsen said, "No comment."

"Nobody believes Andrus had nothing to do with it," said one high Interior official, "but that's the company line."

Herbst said he reviewed the Dodd matter, made his decision without consulting Andrus and finally met with the secretary to inform him of his decision. He said Andrus agreed to the reinstatement.

In a statement Interior released yesterday, Herbst said reinstating Dodd "should clear away a lot of the smoke and confusion that has surrounded the case from its inception."

Much of the "smoke and confusion" apparently originated when Dodd's letter to Dominique's was leaked to The Washington Star's gossip column, "Ear."

Andrus' evident discomfiture led him not only to apologize in person the next day to restaurant owner Dominique D'Ermo, but also to send a written apology later.

On Oct. 11, Dodd was handed a letter of dismissal that included a four-page list of offenses, all based on his own letter.

Among the charges was a accusation that because the Star treated the letter "in a cavalier fashion . . . a serious matter was presented . . . as trivial and frivolous to the public."

Dodd also was accused of using official stationery "which . . . could and did mislead the recipient into believing that your letter represented the official position of the Department."

The snake in question was the Pennsylvania timber ratter. Dodd said biologists had expressed concern about its fate. Andrus, in his letter to D'Ermo, said the animal was "not listed as either threatened or endangered under the Endangered Species Act." Consequently, he said, he knew of nothing to prohibit serving it.

D'Ermo said last night that he is glad that Dodd has his job back. He said he is still serving rattlesnake, but that it comes from texas.