The species of katydid native to Atlantis was relatively large, usually the size of mice, and basically flightless. Before the arrival of Europeans, katydids filled a role in Atlantean ecology similar to that of mice in other parts of the world.
Katydids were edible, if not terribly tasty.
During John James Audubon's 1843 excursion to Atlantis, he observed katydids and how they filled a role similar to mice in most of the rest of the world. His companion Edward Harris found the idea funny, mildly mocking it as something he would consider the next time he saw a six-legged chirping mouse. Audubon laughed but he considered collecting some specimens and did note the notion in his diary when he had a chance.