Tosefta על חולין 268:7

A Kohen is exempt and one who partners with a Kohen [in the profits from an animal] is exempt. An idolater is exempt. One who partners with an idolater is exempt. One who partners with a Kohen needs to make a mark [on the animal]. [One who partners] with an idolater does not need to make a mark, and [as to any animal that is] disqualified from being consecrated, one need not make a mark. [If] a Kohen said to him, "Everything is yours but the foreleg is mine," even [if he said it as to only] one [animal] in a hundred, he is exempt from the [gift of the] shankbone. [If a Kohen said to him,] everything is yours but the intestines are mine, even [if he said it as to only] one [animal] in a hundred, he is exempt from the [gift of the] maw. In a place where they are accustomed to skin the head [of an animal], they are not permitted to skin the cheeks, and [in a place where they are accustomed to] scald a calf [in boiling water], they are not permitted to scald the shankbone and if there is a Kohen [nearby], they give [the priestly gifts] to the Kohen, and if not, they convert [their value] to money [and give the money to a Kohen when one is found]. § [If a butcher] sold the foreleg as it is (i.e., fully intact), the head as it is, or the intestines as they are -- they give [the gifts] to the Kohen, and they do not deduct their value from what they owe to the butcher. [If] they bought by weight, they give [the gifts] to the Kohen and they may deduct their value from what they owe to the butcher. § The gifts do not have any holiness, and they may even be sold [by the Kohen] to an idolater, or even given to his dog. They are not subject to any commandment except to give them to the Kohen. § One who sends meat to his fellow, and and there were gifts in it, they need not be concerned lest they are priestly gifts.