Unregistered

I have a piece of artwork in our collection that I have been unable to identify. It is A Spanish-Mexican scene of a colliseum. The forefront displays a bull and man on a horse. The back left corner has a matador and a man riding a horse. It is a sketch. The only identification on the piece is a handwritten #27 in the upper right corner, and a seal with the letter "N" in the bottom right corner. Any help would be appreciated. I can be reached at daniellej@reaganranch.org

Thanks!