THERE is one passage in the report of Prof. Mivart's lecture on chamæleons (NATURE, vol. xxiv. p. 338) that I cannot allow to pass without demurring to, and that is the suggested probability of a “double origin” for the class Aves. I do not wish at present to raise the issue as to how far the division of all living birds into two groups—“Ratite” and “Carinate”—is, or is not, a natural one; for at present we have not, I think, sufficient information or evidence on the subject to allow of any very definite reply. But anyone who is acquainted with the structure of a Tinamu will, I think, be unable to conceive of the many resemblances that group of birds presents to some of the “Ratitæ” as having been developed independently of any genetic connection between the two—and that is what Prof. Mivart's suggestion practically amounts to. That structures so peculiar as feathers—which, as far as we know, are absolutely confined to birds, though universal amongst them—should have been twice over developed, is to me in the highest degree improbable—as improbable, almost, as that the resemblances of the Tunicates and Amphioxus to the rest of the Chordata should also be accidental.

Affiliations

1. West Wickham, Kent

   • W. A. FORBES

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DOI

https://doi.org/10.1038/024380b0

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