Note 112 — Chapter VIII · THE MAMMALIA OR MILK-GIVERS. The Simplest Suckling Mother, the Active Pouch-bearers, and the Imperfect-Toothed Animals.

This argument, which can only be stated very roughly here, must not be supposed to rest merely on the quadrate bone, though this is the easiest point to illustrate popularly. I am deeply indebted to Mr. W. Kitchen Parker for a whole flood of light thrown on these early forms, and only regret that I have neither skill nor space to do justice to his graphic illustration of a subject of which he is pre-eminently master.