The second IC added "Delete 'remarkable!' An extremely large nebula, 3 ± degrees in diameter, the densest part 12 arcmin southwest of the star 15 Monocerotis (per Barnard and Roberts)". (Per Steinicke, the cluster itself is about 40 arcmin across.) NGC 2264 is part of a complex region in Monoceros, consisting of dark absorption nebulae, emission nebulae, reflection nebulae, and the stars which illuminate or outline their structures. At one end, the Cone Nebula is a dense cloud of gas and dust sculpted by stellar winds from an extremely hot, bright star which is completely hidden in visible light by the gas and dust in front of it. Scattered across the nebula are a number of bright stars which look like lights strung on a Christmas tree, with the Cone Nebula at the apex of the tree, and the bright star S Monocerotis and the Fox Fur Nebula near the base. (The Fox Fur nebula is not generally considered a part of NGC 2264, but is certainly an extension of the gas and dust filling the region, as all the stars and clouds of gas and dust lie at about the same 2600 light year distance from us.
     The field of view below, extending from the Cone nebula at the top to S Monocerotis and the Fox Fur nebula at the bottom, covers about 30 light years. (ESO)

Below, a HST closeup of the Cone Nebula shows the dense clouds of gas and dust in a region only a couple of light years across (the overall size of the Cone is about 7 light years). The stars near the tip of the Cone are not responsible for its shape. That is sculpted by stellar winds from an extremely bright star, NGC 2264 IRS, first seen in a 1997 Hubble image, and dramatically shown in a more recent Spitzer image, further below. (ACS Science & Engineering Team, NASA, apod020503)

Below, a Spitzer Space Telescope infrared image showing NGC 2264. The brilliant star near the Cone nebula is NGC 2264 IRS, the source of the stellar winds sculpting the Cone. Despite its brilliance, this star is completely hidden by the gas and dust in front of it. Only infrared images can penetrate the dust and reveal the star; but when they do, its brilliance dwarfs that of the other stars in the region. (NASA, JPL-Caltech, P. S. Teixeira (CfA), apod070509)

At the opposite end of NGC 2264 from the Cone nebula, the Fox Fur Nebula, though not technically a part of NGC 2264, reveals a complex structure of clouds of gas and dust. The bluish glow of the gas to its right is caused by light scattered from the nearby star S Monocerotis, which is outside the field of view, but visible in the full-field images at the top of this section. (Jean-Charles Cuillandre (CFHT) & Giovanni Anselmi (Coelum Astronomia), (copyright Hawaiian Starlight, used by permission) apod080422)

The second IC adds (per Delisle Stewart) "Two nebulae close together". Apparent size about 1.7 by 1.3 arcmin.

Based on recessional velocity of 2415 km/sec, about 110 million light years away, in good agreement with a redshift-independent distance estimate of 120 million light years. Given that and apparent size of 2.8 by 2.7 arcmin, about 90 thousand light years across.

Per Dreyer, NGC 2287 (= Flamsteed, Legentil, M14, 1860 RA 06 41 00, NPD 110 36.0) is a "cluster, very large, bright, a little compressed, stars from 8th magnitude". The reference to M14 is wrong, and was corrected in the first IC, which stated "For M14 read M41".