genetic stages in common are we justified in inferring that their racial ancestor may have had such characters in the adult state. But it should never be lost sight of that this inference is only a provisional hypothesis which may or may not be verified when the paleontologic record is more complete. It is no surprise that the efforts of some earnest paleontologists have been discredited in some quarters, especially among zoologists. Some of them have invoked recapitulation as a sort of magic spell by which they can conjure up ancestral forms from almost any embryonic series, forgetting the limitations of this doctrine. As far as the attitude of vertebrate paleontologists is concerned, their view has been aptly summarized by Professor Charles Depéret in his book "Les Transformations du Monde Animal" and I can do no better than close with a quotation from him: