Two very similar species of tree monitors, both members of the subgenus Euprepiosaurus. At left is the black tree monitor, Varanus beccarii, with smooth head scales, with a large central series; at right is the Bogert's tree monitor, V. bogerti, with rough head scales all subequal in size. Not that Bogert's monitor has a broader temporal region and lighter snout tip. Photo by Dr. Robert Sprackland.