Part 30

Rivers, Mississippi, 86, 89; Hoang-ho, Ganges, Thames, 87; alterations made by, 87.

Rocks, crystalline or plutonic: sedimentary, 85; eruptive, 88; new, 59; of Grand Canon, 90; testimony of, establishes evolution, 100.

Salamanders, 45, 46.

Salts, of sodium, chlorine, magnesium, potassium, 24.

Samoan Islands, 103.

Sandstone, 90.

Science, what is it? 5, 6; physiological, 14.

Sea anemones, 68.

Sea elephant, 38.

Seals, 38, 39, 40, 209.

Selection, natural, doctrine of, 116, 117, 118; struggle for existence, 124, 125; simply trial and error, 131, 136, artificial, 136, 137, 138; laws of, in mental phenomena, 203.

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

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

Shale, 89.

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

Sheep, 157.

Simiidae, 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.

Solomon Islands, 103.

Species, origin of human, 153.

Spencer, Herbert, 8.

Squirrels, evolved from terrestrial rodents, 14; 41; flying, true rodents, 41.

Starch, 24.

Stephenson, 10.

Strata, 88, 89; arranged according to ages, 89; 90; time of formation, 92.