[92] Ichthyornis, fish-bird.

[93] Hesperornis.

[94] Some chamæleons and geckos also have air-tubes passing from the lungs into the body, and the crocodile’s skull is full of air-cells; but the two phenomena are not connected as in birds, and other parts of the skeleton or of the skin-covering, being heavy, have a counteracting effect.

[95] This third eyelid is a fold on the inner side of the eye; some reptiles and amphibians have it, and so have the marsupials and many of the higher animals.

[96] Struthio camelus.

[97] Dinornidæ, of which Dinornis, a still more ancient form, must have been ten feet high.

[98] This beautiful effect may be seen from below when the guillemots are fed in any of the public aquariums.

[99] Talegallus.

[100] Megapodidæ or large-footed birds.

[101] Partridges, quails, and some others are exceptions, and pair.