The rump. Rather, "the tail." Oriental sheep have very commonly a broad fat tail, which weighs from six to twenty pounds, and is sometimes laid upon a little cart with two wheels, which the sheep drags after it.
There is no doubt that a "tail" of this kind is here meant. The caul. Rather, "the membrane." See the comment on Exodus 29:13. The right shoulder. Or "leg," according to some. The difference is not important.