Varro (1st century BC)[REF] distinguishes among the di superi ("gods above"), whose sites for offerings are called altaria; the di terrestres ("terrestrial gods"), whose altars are arae; and di inferi, to whom offerings are made by means of foci, "hearths," on the ground or in a pit.
Thus victims for public sacrifices were most often domesticated animals that were a normal part of the Roman diet, while offerings of victims the Romans considered inedible, such as horses and puppies, mark a chthonic aspect of the deity propitiated, whether or not the divinity belonged to the underworld entirely.