Figure 1.

Schematic Representation of Major Muscle Systems of an Adult Polyplacophoran and the Neomeniomorph Aplacophoran Wirenia argentea

Polyplacophoran myoanatomy is highly conserved; thus, the schemes serve as a generalized model for the entire class. Note that in some neomeniomorphs (but not in Wirenia), distinct enrolling muscles are present. Individual muscle units are indicated by color code, with homologous muscles sharing the same color. The body wall musculature (light blue) of Wirenia in (B) and (D), which comprises ring, diagonal, and longitudinal muscles, is represented by only the ring musculature for clarity. The dorsoventral musculature (purple) is depicted as dots to indicate its major dorsal insertion sites in (C) and (D).

(A) Leptochiton asellus, cross-section.

(B) Wirenia argentea, cross-section.

(C) Leptochiton asellus, dorsal view.

(D) Wirenia argentea, dorsal view.