It seems clear that the upper and lower halves of the present piece were not originally designed to go together. The bottom element appears to be Venetian or Paduan in origin and to derive ultimately from the works of Riccio and Severo da Ravenna. By contrast, the group of Hercules and Cacus represents an interesting example of a Paduan model being adapted and developed in the Vischer workshop. The kneeling figure of Cacus is taken directly from the kneeling Hercules or Atlas figures which serve as supports for inkwells and oil-lamps and which were produced in the workshop of Severo da Ravenna. Wixom lists several examples of this type (loc. cit., as workshop of Riccio), many with variant details.
The facial features of Hercules are rendered more summarily than the careful delineation typical of Severo and his workshop, and this figure has been added to create a Hercules and Cacus group in the tradition of the Vischer workshop, as with the Hercules and Antaeus by Peter Vischer in the Bayerisches Nationalmuseum, Munich (H. Weihrauch, Europäische Bronzestatuetten - 15.- 18. Jahrhundert, Braunschweig, 1967, fig. 321).
Another, closely related version of this group was lot 119 in a Sale of Important Renaissance Bronzes, Sculpture and Works of Art on 15 May 1984 in These Rooms. The only significant respect in which it differed from the present bronze was in showing Cacus's left hand resting on his knee as opposed to with the palm flat on the ground as is almost invariably the case with examples of Severo's model.