Later in the juvenile stage the living chamber grows proportionally longer .
Later in the juvenile stage the living chamber develops a median dorsal and two lateral keels and has an aperture with a receded ventral or lower lip ( B.R. &S ) .
Later in the juvenile stage the living chamber grows proportionally longer and develops a median dorsal and two lateral keels and has an aperture with a receded ventral or lower lip ( B.R. &S ) .