Sterility of hybrids, [125].

Stings, [66].

Straining action of baleen, [41].

Struthious birds, [70], [151].

Sturgeon, [171].

Suarez, [18], [263].

Substantial forms, [186], [272].

Sufferings of beasts, [260].

Supernatural action, [252].

Supernatural action not to be looked for in nature, [15].