Graphic representation of the data in Table 3. Each panel illustrates the number of Class II (red) and Class III (blue) objects of a given age projected onto one of the six NGC 2264 subregions shown in Fig. 10. The x-axis coordinates correspond to the median isochronal ages computed for Class II and Class III objects in each age bin. The y-axis values can be derived from Table 3 by multiplying the total number of objects at a given age by the corresponding percentage in each region. The vertical error bars correspond to the Poissonian errors on the counts in each bin.