"Portions of sections through the disc of medusae. The upper one of Lizzia, the lower of Aurelia. el,…
"Muscular cells of medusae (Lizzia). The uppermost is a purely muscular cell from the sub-umbrella;…
"Two female sporosacs (degenerate medusae) of Hydraetinia echinata. a, ectoderm; b, endoderm; o, eggcella;…