Distribution, on the H-R diagram, of CTTS (left panel) and WTTS (right panel) in NGC 2264 with period measurements from the present study. A color scale, proportional to the period as indicated on the side axis to the right of the diagrams, is used to fill the symbols of each source. Mass tracks shown on the plots, truncated at an age of 30 Myr, are from Siess et al.’s (2000) evolutionary models.