We present results from 1078 high resolution spectra of 990 stars in the young open cluster NGC 2264 , obtained with the Hectochelle multiobject echelle spectrograph on the 6.5m MMT .
We confirm 471 stars as members , based on their radial velocity and/or H \alpha emission .
The radial velocity distribution of cluster members is non-Gaussian with a dispersion of \sigma \approx 3.5 km s ^ { -1 } .
We find a substantial north-south velocity gradient and spatially coherent structure in the radial velocity distribution , similar to that seen in the molecular gas in the region .
Our results suggest that there are at least three distinguishable subclusters in NGC 2264 , correlated with similar structure seen in ^ { 13 } CO emission , which is likely to be a remnant of initial structure in this very young cluster .
We propose that this substructure is the result of gravitational amplification of initial inhomogeneities during overall collapse to a filamentary distribution of gas and stars , as found in simulations by Burkert & Hartmann ( 4 ) .