BRIDGEPORT, Conn. (AP) _ Two former Choate Rosemary Hall students admitted in court Thursday to smuggling 350 grams of cocaine from South America with money collected from classmates at the exclusive preparatory school.

Two other former students pleaded guilty to misdemeanor charges in the case, and the pleas brought to 16 the number of former Choate students who have admitted taking part in the scheme.

Derek Oatis, 19, of Meriden and Catherine N. Cowan, 19, of Little Rock, Ark., each pleaded guilty before U.S. District Judge T.F. Gilroy Daly to one felony count of importing a controlled substance.

Randall S. Zuckerman, 19, of Easton, and Marcie Lara Riveles, 19, of New Fairfield, pleaded guilty to misdemeanor charges of aiding and abetting in the possession of cocaine.

The government is planning to file misdemeanor charges against at least eight more past or present students for allegedly contributing money to send Miss Cowan and Oatis to Venezuela to buy the drug, U.S. Attorney Alan H. Nevas said.

Oatis and Miss Cowan were arrested April 23, 1984, by customs agents at Kennedy International Airport in New York after returning from Venezuela. A government indictment said they bought 350 grams of cocaine in Caracas with $4,800 collected from schoolmates.

Nevas said he would recommend prison terms for Oatis and Miss Cowan at their sentencing in November, but has not decided whether to recommend imprisonment for those charged with misdemeanors.

Attorneys for Miss Cowan and Oatis said they hoped for ''non-jail'' sentences. The charges against them carry a maximum penalty of 15 years in prison, a $25,000 fine and lifetime probation.

Zuckerman, who admitted giving Oatis or Miss Cowan $200 on behalf of himself and others for cocaine, and Miss Riveles, who admitted contributing $40, face maximum penalties of one year in prison and $5,000 fines. They and 12 others charged with misdemeanors have been released on their own recognizance and Daly deferred a guilty finding.

Under the aiding and abetting charge, a sentencing judge can place a defendant on probation for a year without issuing a guilty finding.