Final answer:
The victim was wearing a motley costume with a parti-striped dress, conical cap, and bells on his head. This attire is often associated with jesters or fools during the carnival season.
Step-by-step explanation:
The victim was wearing a motley costume when the narrator meets him. The term 'motley' refers to a costume or outfit that is made up of different colors or patterns. In this context, it means that the victim was wearing a multi-colored or parti-striped dress with a conical cap and bells on his head. This attire is often associated with jesters or fools, and it adds to the sense of madness and chaos during the carnival season.