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Show 468 PROF. HUXLEY ON THE CLASSIFICATION OF BIRDS. [Apr. 11, Sundevall* proposed to break it up into the three distinct groups of PICI, PSITTACI, and COCCYGES,-the first to contain Picus and Yunx; the last Pogonias, Bucco, Crotophagus, Phcenicopheeus, Coccyzus, Centropus, Cuculus, Galbula, Dacelo, Merops, Colaris, Trogon, and Caprimulgus. Sundevall calls these groups "orders;" but, leaving the question of taxonomic rank aside, the first two exactly correspond with the Celeomorphae and Psittacomorphae of the present essay; while the third nearly answers to m y Coccygomorphae,-a coincidence which I the more desire to signalize, as the Swedish naturalist attends only to external characters, while I have, almost exclusively, been guided by the skeleton. Kesslerf takes very much the same view as Sundevall, though he is inclined to put Bucco along with the Woodpeckers, instead of arranging it, as Sundevall more justly does, with the Cuckoos. Not that the resemblances pointed out by Kessler do not exist; they are genuine enough, just as are others which might be pointed out between the Woodpeckers and the Hornbills and other Coccy-gomorphae; but the structure of the skull affords a very definite and complete distinction between the latter and any of the Gecino-morphae. The Woodpeckers, in fact, are not Desmognathous, the palate in these birds exhibiting rather a degradation and simplification of the iEgithognathous structure. The vomers retain throughout life the condition which is transitory in the Coracomorphse. With the latter the Celeomorphae have in common the shortness of the wing-coverts, the conical scapula; accessoria;, the bifurcate manubrium of the sternum, the multiperforate backward process of the tarso-metatarsus, and the brevity of the basal phalanges of the toes as compared with the penultimate. Thus I conceive that the Celeomorphae are intermediate between the Coracomorphse and the Coccygomorphae, and that they may be best associated with the former as an aberrant group of the iEgitho-gnathae, tending towards the Coccygomorphae as the Cypselomorphae do in another way. The other ^ E G I T H O G N A T H ^ E are divisible into two groups, the C Y P S E L O M O R P H A E and the C O R A C O M O R P H A E. The CYPSELOMORPHAE, like the Gecinomorphae, are annectent forms between the Coracomorphae and the Coccygomorphae. The vomer is truncated at the anterior end, and the maxillo-palatines slender and disposed nearly as in the typical Coracomorphae (? Trochilus). The sternum is broad and is devoid of a forked manubrium. Its posterior edge may be entire, or may have two excavations on each side. The furcula has no backwardly directed median process, or only a * Ornithologiskt System af C. J. Sundevall, Kongl. Vetensk. Akad. Ilandlimrar 1835, p. 68. b ' t '* Beitrage zur Naturgeschichte der Spechte," Bulletin de la Societe Impe-riale des Naturalistes de Moscou, 1844, pp. 331-340. |