CHAPTER XVII ON THE THEORY OF TRANSFORMATIONS, OR THE COMPARISON OF RELATED FORMS

from the group of Perissodactyle {760} Ungulates, the group which includes the rhinoceros, the tapir, and the horse.

A series of five diagrams illustrating the transformation of a fish's pelvic bone shape, from D'Arcy Thompson's 1915 work.

Let us begin by choosing as our type the skull of Hyrachyus agrarius, Cope, from the Middle Eocene of North America, as figured by Osborn in his Monograph of the Extinct Rhinoceroses¹⁸ (Fig. 394).

The

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