. La structure et la classification des oiseaux . I. 1, à l'exception de l'autruche, du Numenius et du canard embryonnaire,^où le chiffre III a une petite phalange supplémentaire. Chez les autres oiseaux, la formule est I. 2, II 3, III 1, et dans l'apteryxdigit II montre trois phalanges au cours de son développement - Paekbe, sur la structure et le développement de l'escadre dans le CommonFowl, Phil. TRANS. 1888, p. 385, où la littérature précédente est citée. Baue, Science, vol. C. p. 355. 126 STRUCTURE ET CLASSIFICATION DES OISEAUX, dont l'un (apparemment le milieu) n'est pas reconnaissable chez l'adulte. Lbighton a co

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. The structure and classification of birds . I. 1, with theexception of the ostrich, Numenius, and the embryo duck, ^where digit III. has a small additional phalanx. In otherbirds the formula is I. 2, II. 3, III. 1, and in the apteryxdigit II. shows three phalanges in the course of its develop- Paekbe, On the Structure and Development of the Wing in the CommonFowl, Phil. Trans. 1888, p. 385, where previous literature is quoted. Baue, Science, vol. v. p. 355. 126 STRUCTURE AND CLASSIFICATION OF BIRDS ment, of which one (apparently the middle one) is notrecognisable in the adult. Lbighton has contributed to this question with a studyof the development of the wing of Sternal He finds heretoo a rudimentary fourth digit, which in the first stage, which he figures, is as long or nearly as long as the firstdigit. A rudimentary metacarpal even persists attached tothe side of the last metacarpal in birds just before hatching.In the carpus there are never more than four distinctcartilages ; there are in the first place a radiale and ulnare, . Fig. 71.—Dibits of Ostrich (aftee Wrai). I, phalanx 1 (/%!) and rudimentary phalanx 2 (PhU) of digit III.; c, connective tissue.2, another specimen with phalanges ankylosed. 3, distal part of digit III. ofembryonic manns (4). and distally two cartilages, of which one appears to representthe combined distalia of the two first digits, and the secondthat of the third digit. In birds, just before hatching, allthe distalia have fused into one mass. The cartilageslettered respectively radiale and ulnare in the figures arethought, however, by the author to be really radiale +intermedium and ulnare + centrale ; and in support of thisview is the partial separation between the two supposedelements of each, which is, however, never carried veryfar. As to the homologies of the digits in the adult with those The Development of the Wing of Sterna Wilsonii, Tufts Coll. Studies, 1894. Previous literature is here quoted. OSTEOLOGY 127 of the reptilian han

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• bookdecade1890
• booksubjectbirds
• bookyear1898