The second movement is a lateral torsion of the visceral mass, the foot remaining a fixed point; this torsion occurs in a plane approximately at right angles to that of the first movement, and carries the pallial aperture and the anus from behind forwards.
Finally, the original symmetry of the circumanal complex vanishes; the anus leaves the centre of the pallial cavity and passes towards the right side (left side in sinistral forms); the organs of this side become atrophied and disappear.
The pallial cavity, with its organs, is by this torsion moved up the right side of the larva to the dorsal surface, and thus the left organs become right and vice versa.
Pac, Pallial cavity.
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