Xenorhynchus, fossil, [99];

X. australis, [98]

Xerophila, [539], [540]

Xipholena, [480];

X. pompadora, [480]

Xiphorhamphus, [502], [504]

Xiphorhynchus, [484], [487]

Yaffle, [460]

Yarrell's British Birds, [212] n., [285] n.

Yellow colour in Birds, its nature, [3] n.