Well... you weren't exactly assaulted. An assault is an attempt to make unwanted physical content or a threat on you. The correct crime would be battery.
You should have told the driver since most buses come with cameras built into them. However without any video, the police really can't do much. The reason I say it is because most police departments are bogged down with calls which are prioritized based on the severity of the situation. The chances of catching him are slim.
Also you should check the bite areas. Might want to see the hospital if any of the skin got broken.
