Sequence, physiological, in training animals, 209; 210.

Series,
sedimentary, 84, 90, 92;
crystalline or plutonic, 85;
Azoic or Archæan, age of, 92.

Shale, 89.

Shark,
common, most fundamental form, 46;
embryo of, hammerhead;
embryos of, 66.

Sheep, 157.

Simiidæ, 160, 163.

Skate, embryos of, 66.

Snails, 45; shells of, 95; land snails, 103; Hawaiian and Polynesian, 104.

Society Islands, 103.

Solar system, origin of, 84.