WASHINGTON — With the nation riveted by the embattled Supreme Court nomination of Judge Brett M. Kavanaugh, the court itself returned to the bench on Monday to start a new term after the justices’ summer break.

There was no empty chair to mark the absence of a ninth justice, and no mention of the confirmation fight. Instead, Chief Justice John G. Roberts Jr. started the session with a nod toward continuity, noting that it was the 25th anniversary of Justice Ruth Bader Ginsburg’s investiture. “We all look forward to sharing many more years with you in our common calling,” the chief justice said.

Justice Ginsburg, who is 85, smiled and nodded.

Soon afterward, the eight justices turned their attention to the fate of the dusky gopher frog. They discussed draining the swamp, but not as a figure of speech.

The species is in danger of extinction, and the only known remaining frogs live in the De Soto National Forest in Mississippi. In 2012, the federal government came up with a backup plan, designating private land in Louisiana as “critical habitat” for the frogs’ survival. None of the frogs live there now, and the designation could limit the ability of the owners to develop the land, by one account potentially costing them about $33 million.