Fig. 1
From: Shell field morphogenesis in the polyplacophoran mollusk Acanthochitona rubrolineata
Polyplacophoran shell plates and their development. a Adult A. rubrolineata; dorsal view with the anterior to the top. The eight serially arranged shell plates (arrows) are encircled by the girdle (double arrow). b Generalized scheme depicting polyplacophoran shell ontogenesis. In some species, the newly hatched trochophore larvae do not have a recognizable shell field. After metamorphosis, seven calcified shell plates emerge in the juvenile (arrows) and spicules develop in the girdle (the double arrow). Developmental stages are referred to A. rubrolineata