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Show 1867.] PROF. HUXLEY ON THE CLASSIFICATION OF BIRDS. 469 rudiment of it; and the scapular end of each clavicle is not expanded and T-shaped. The lower larynx has not more than one pair of intrinsic muscles. This group contains three very distinct families-the Trochilidee, the Cypselidee, and the Gaprimulgidee. The first two families have a length of the manus and a brevity of the humerus which is peculiar to themselves, being only approached by the Swallows, and in a less degree by the Gaprimulgidee. In both Caprimulgus and Mgotheles the manus is slightly longer than the ulna, and the latter considerably exceeds the humerus in length. Both the Swifts and the Goatsuckers have a slight rudiment of a. vertical process developed from the middle of the furcula. Afgo-theles approaches the Swifts more nearly than Caprimulgus does in the form of its palatine bones, and in the absence of basipterygoid processes. The Cypselidee are very closely related to the Swallows among the Coracomorphae, while the Caprimu/gidee come near Trogon, and more remotely approach Podargus and the Owls. The CORACOMORPHAE. There are no basipterygoid processes. The vomer, single in the adult, is truncated in front and deeply cleft behind*. The maxillo-palatines are sometimes slender and rod-like, sometimes broader, but are never concavo-convex lamellae, or tumid and elongated as in most Schizognathae. The posteroexternal angles of the palatines are always well marked, and are frequently produced backwards. The sternum has a forked manubrium, a strong carina with an excavated anterior edge, long costal processes, and, except in one or two cases (Pteroptochus and Scytalopus), its posterior edge has a single notch on each side. The clavicles have expanded T-shaped scapular ends, and send back a vertical process from their inferior junction (except in Menura). There is a conical scapula accessoria. The tarso-metatarsus has a tuberosity perforated by six distinct canals for the flexor tendons. The pollex is strong and turned backwards. The basal phalanges are not longer than the penultimate, but usually much shorter in the anterior toes. The contour-feathers have a small aftershaft, and the oil-gland has no circlet of feathers. There is only one carotid, the left. The lower larynx presents every degree of complexity. It may be wholly tracheal, or, as is more commonly the case, partly tracheal and partly bronchial; it may be devoid of muscles, or may have six pairs, or may be enveloped in a muscular mass. * Nitzsch (Art. Passerinae, Ersch und Griiber's ' Encyclopaedic,' 1840) was the first to indicate this and many other distinctive characters of this group. |