Back, or tenon saw
Back saw (made from an old hand saw) or tenon saw.
This saw is sometimes known as a tenon saw or a back saw. Tenon saws are used for making the male tenon joint and general bench work. They are made' cross cut'cutting across the grain of the wood. This saw appears to have been a hand saw converted to being a back saw by reducing its length and fitting the back rib or cap.