transversal to the body axis, and each serial covers completely the ventral region between the
posterior edge of the o.articulare-angulare (Oaa.) and just before the gill slit. Radii
branchiostegi (R.) adheres laterally to the outer surface of this muscle arranging arciform rows
supported with the membranous tissue. This muscle pulls interiorly the R. by its contraction.
After that, each opercular component is induced to be adducted to shut the gill slit. In Fig. 6,
such muscles relating with the opercular movement as the Maoa., Maop. and Maope. are drawn
to show their constructional relation. Further, their related bones are shown in Fig. 5.
Contracted Maoa. and Maop. abduct the Oop. and its connected bones through the membranous
or tendon tissues at the two fulcra (Jl. and J2. in Fig. 5). The Maope. adducts the opercular
components at the above mentioned fulcra