Torga, 183.

Tortoise, soft shelled, of the Mississippi, 45.

Tower, 148.

Transformation, natural, 170.

Tribes, 32.

Tuberculosis, bacillus of, 127.

Turtles, evolution of, 45.

Ungulates, 65.

Uniformitarianism, Lyell's doctrine, 80.

Urea, 29.