Ulna, [8], [8];

its quills, [22]

Umbrella-bird, [481], [481]

Umbrette, [70]

Unfeathered spaces, or apteria, [2]

Uncinate process, of ribs, [6], [7];

absent in Archaeopteryx, [23];

in Palamedeidae, [108]

Upper arm-bone, [8]

Upucerthia, [486]