Which membrane of the gizzard serves as a protective layer (magin)

Description

The Chasam Sofer rules against Maharim Chagiz, holding that the thin green membrane in a goose's gizzard is part of the white inner protective layer and does function as a magin, rendering the bird kosher when the puncture does not penetrate through it. He further sharply rejects a correspondent's anatomical reversal of the gizzard's inner and outer layers, citing the Rambam, Bartenura, and Sefer HaChinuch, and warns that this error would lead to catastrophic misidentification of kosher and non-kosher birds.