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Show 1889.] MR. W. K. PARKER ON STEATORNIS CARIPENSIS. 163 Classification of Birds was being written, I pointed out to Professor Huxley that even in the Gallinaceous tribes, which are, more than any other birds, most distinctively " Schizognathous," the larger Curassows, e. g. Grax globicera, are " Desmognathous." I have since that time discovered that Dicholophus is directly Desmognathous1. If we then bind up together some two dozen families of arboreal birds of the higher, but not highest kinds, and call them " Coccygomorphae," we must use the palatal character for just what it is worth and no more. If all these troops are to march under the Huxleyan standard, then we shall have the following palatal characters in this mixed multitude of birds : - SCHIZOGNATHISM.-Trochilidae, Trogonidae, Caprimulgidae (part.). ^EGITHOGNATHISM.-Cypselidae. D E S M O G N A T H I S M . - ( a . Indirect).-Coliidae. (b. Imperfect direct).-Capitonidae. (c. Perfect direct). - Rhamphastidae and many others. (d. Double).-Bucerotidae (part.), Steator-nithidae, Podargidae. S A U R O G N A T H I S M \-Picidae, Yungidae. So, again, with regard to another of the deep morphological characters, namely, the arrest or development of the " basipterygoids "; in this character we have the extremest difference, for Steatornis is almost Struthious in this respect, and Cuculus (amongst others) has these parts aborted as much as in the Passeres, in which they very seldom show a trace in the adult. Another deep and diagnostic character is the peculiar articulation of the centra of the vertebrae, between the axis and the sacrum3. This, as a rule, is what is called cylindroidal by Prof. Huxley, and hetero-ccelous by the American ornithologists. Now it has long been known that many Water and Wading birds have their thoracic or dorsal vertebrae of the archaic type-like those of ancient reptiles, they are opisthoccelous. But I long ago showed that Parrots have the same structure, combined with an anticipation of the Mammalian centrum, namely with terminal epiphyses. But more lately I have discovered that the dorsals of Steatornis are opisthoccelous also. This fact has softened down my objection to putting the Parrots along with the other Zygodactyles and their Syndactyle relatives ; they are not more isolated than the Humming-birds and the Swifts. The manner in 1 In my paper on the Bird's Skull, Linn. Trans, new series, Zool. vol. i. p. 129, pi. xxv., I have described the palate of this bird as being imperfectly desmognathous; the bony union of the " maxillo-palatine plates" is, however, perfect in m y specimen. 2 Strictly speaking the yEgithognathous and the Saurognathous palates are merely varieties of the Schizognathous type; that reduces the whole thing to two main kinds-the Schizognathous and the Desmognathous; the " Hro-mseognathous " condition is merely a retention in the adult of an early embryonic a&Proc. Roy. Soc. 1888, pp. 465-482. |
