A circular saw blade assembly of a tree felling head of a type which has peripherally mounted cutting teeth. The assembly has a circular disc plate with a rim. Mounting lug arrangements evenly distributed and outwardly projecting around the rim receive tooth holders having respective heads adapted to receive the cutting teeth, and respective shanks projecting behind the heads and adapted to receive bolts for fastening the cutting teeth against the heads of the tooth holders. Each mounting lug arrangement has opposite lug elements spaced from each other and extending in parallel with a radial plane of the disc plate. The lug elements of each mounting lug arrangement define an outwardly opened channel extending substantially in a tangential direction with respect to the rim and into which the shank of one of the tooth holders is slideably mountable.