Bartholinus, Heister, Hufeland, Morgagni, Riolan, and Sandifort cite examples of duplex stomach.

Bonet speaks of a case of vomiting which was caused by a double stomach.
Struthers reports two cases in which there were two cavities to the stomach.

Struthers also mentions that Morgagni, Home, Monro, Palmer, Larry, Blasius, Hufeland, and Walther also record instances in which there was contraction in the middle of the stomach, accounting for their instances of duplex stomach.

Musser reports an instance of hour-glass contraction of the stomach.

Hart dissected the stomach of a woman of thirty which resembled the stomach of a predaceous bird, with patches of tendon on its surface.