Figure 6.

Lepisosteus osseus. Stages 21-24. A) Stage 21. B) Stage 22. C) Stage 23. D) Stage 24. ff= fin fold cl = cloacal aperture ot = otic vesicle ol = olfactory placode op = operculum ao = adhesive organ sgc = limit of subgerminal cavity y = yolk sac ba = branchial arch