A motorcycle rider who hit a car in Naples Saturday remained in critical condition at Maine Medical Center Sunday, a spokeswoman said.

Tony Shibles, 48, was not wearing a helmet, according to investigators with the Cumberland County Sheriff's Office. He was passing cars on Route 302 in Naples yesterday when he hit a car being driven by 33-year-old Michael Porraro.

Investigators said they believe Porraro was traveling the same direction as Shibles.

The exact cause of the accident is under investigation.