[112] 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.
[113] Diprotodont.
[114] The only exceptions to this are a tooth and a piece of a tusk of one of the ancient elephants, lately found in Australia, showing that a few straggling forms of mammalia probably reached that country in Tertiary times.
[115] Macropus giganteus.
[116] Hypsiprymnus penicillatus.
[117] Dendrolagus.
[118] Phascolomys.
[119] Dasyurus.
[120] Thylacinus.
[121] Didelphis.