TEM sections of specimens of Neoechinorhynchus personatus from Mugil cephalus in the Mediterranean Sea off Tunisia. 23. Cross section of a hook. Note the serrated (corrugated) outer layer and the solid inner core with an internal tube. 24. Higher magnification of pert of the hook in Fig. 23 showing the outer serrated layer. 25. Outermost layer of the hook showing detail toothed serrations. 26. Transition between the neck (top) and trunk (bottom with micropore tubules) of a worm. 27. Outer tegument layer of the neck with a knobby (pebbled) surface. No visible micropore channels here. 28. A high magnification of the neck tegument in Fig. 27. Note distinct outer layer and myofibrils beneath the tegument. 29. Part of the trunk tegument of a worm showing micropore channels. 30. A higher magnification of a section of the tegument in Fig. 29 showing detail of the micropore channels.