Retractor

... following muscles: M. adductor mandibular externus superficialis (yellow); M. levator pterygoideus (purple); M. protractor pterygoideus (red); M. retractor pterygoideus (blue); M. pterygoideus (green). e, ectopterygoid; m, maxilla; pa, palatine; pf, prefrontal; pt, pterygoid. These snakes are ...

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... males have a pair of intromittent organs called hemipenes, protrusible saclike diverticula at the entrance of the cloaca. During copulation, the retractor muscles of the hemipenes relax, turning the sacs inside out and allowing the flow of semen along a groove into the female's cloaca. Only one ...

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