[Pteropoda] Line between the lateral side of the aperture and the protoconch or caudal septum; line between spine and lock area visible in ventral view (Cavolinia in ventral view).

[Pisces] A sensory organ of fishes which consists of a canal running along the side of the body and communicating via sensory pores through scales to the exterior; functions in perceiving low frequency vibrations and pressure differences in general.