. 5 is a longitudinal sectional view corresponding to FIG. 4 showing in particular a state in which a first lid for the bottle holder is opened;FIG. 6 is a transverse sectional view showing the structure of the accessory storage with its lid closed;FIG. 7 is a transverse sectional view showing the structure of the accessory storage with its lid opened;FIG. 8 is a perspective view showing the struc