Note 640 — Chapter XVI · ON FORM AND MECHANICAL EFFICIENCY

“There can be no doubt that Fraas is correct in regarding this type (Procetus) as an annectant form between the Zeuglodonts and the Creodonta, but, although the origin of the Zeuglodonts is thus made clear, it still seems to be by no means so certain as that author believes, that they may not themselves be the ancestral forms of the Odontoceti”; Andrews, Tertiary Vertebrata of the Fayum, 1906, p. 235.