sentences:  The lantern, where present, surrounds both the mouth cavity and the pharynx.At the top of the lantern, the pharynx opens into the esophagus, which runs back down the outside of the lantern, to join the small intestine and a single caecum.The small intestine runs in a full circle around the inside of the test, before joining the large intestine, which completes another circuit in the opposite direction.