de Vaucouleurs Revised System

The 3-D system. Principal axis is stage, vertical axis is bar, and the in-out axis is ring. The overall shape indicates the maximum variety occurs in the middle of the spiral sequence. (click to enlarge)

 

Cut through the 3-D system near Sb; sketches to illustrate the features.

 

Ditto, with example galaxies inserted.

 

Figures taken from deVaucouleurs 1959 article in Handbuch der Physik [o-link]