BOSTON — Transit officials say a 3-foot-long boa constrictor that slithered away from its owner on a Boston subway car a month ago was found on an adjoining car Thursday.

A commuter spotted Penelope the snake and alerted a train attendant at a Red Line station. Transit authority officials took the train out of service to search it. Finally at 8:30 p.m., train attendant Sharon Lynch — a snake owner herself — caught the snake.

Penelope’s owner, 30-year-old Melissa Moorhouse of Allston, had traveled around with the snake around her neck and lost it between two stations Jan. 6. She’s thrilled to have her pet back, and says she’ll pay more attention the next time she takes Penelope out in public.