. The Auk . al opening. Later on theascending process ossifies, forming a tri-radiate bone, extremelywell marked in Panyptila. The interorbital portion of the frontals *See, however, foot-note on page il. lO Lucas, the Mai>i Div/siotis of the Sivifts. [January is comparatively wide, slightly sviggesting Caprimulgus in itsoutline. Viewed from below the elongation of the rostrum is verynoticeable while the pre-maxillaries are seen to run well back-ward, thus contrasting with the other Swifts and once more sug-gesting Caprimulgus. Dendrochelidon has the characteristic unciform maxillo-palatine
. The Auk . al opening. Later on theascending process ossifies, forming a tri-radiate bone, extremelywell marked in Panyptila. The interorbital portion of the frontals *See, however, foot-note on page il. lO Lucas, the Mai>i Div/siotis of the Sivifts. [January is comparatively wide, slightly sviggesting Caprimulgus in itsoutline. Viewed from below the elongation of the rostrum is verynoticeable while the pre-maxillaries are seen to run well back-ward, thus contrasting with the other Swifts and once more sug-gesting Caprimulgus. Dendrochelidon has the characteristic unciform maxillo-palatines of the Swifts, but the palatines and vomer differ totallyfrom the Cypseline pattern. The pre-palatine bar is narrow, in-stead of wide, the external palatine notch is wanting, and thetrans-palatine portion is entirely different in shape from that ofthe other Swifts, being not unlike Capriimdgus. The anteriorlyT-shaped vomer of the other Swifts is replaced by a vomer thatis scarcely expanded at all Fig. I. Fig. 2. Fig. 3. Ventral aspect of crajiia. of I. Anirosiomtis voci/erus, z. Dendrochelidon mystacea, , all enlarged to the same absolute size. V, vomer; mxp, maxillo-palatine; pi, prepalatine; ee, ecto-ethmoid; tpl, trans-palatine ; pg, pterygoid ; q, quadrate ; s, sphenoid; bt, basi-temporal. One maxillo-palatine is omitted to better show the vomer. Owing to foreshortening the length of the rostral portion of the skull of Dendrochel-idon is apparently not so great as it is in reaUty. The sphenoid of Dendrochelidon partakes of the general elon-gation of the skull, and the articulations of the pterygoids withthe sphenoid are brought well forward, and form a rather sharpangle with one another. This is a departure from the Cypselinestructure, in which the pterygoids are closely applied to the basi-temporal, and a step toward the Passerine arrangement. iSSy.] Lucas, the Alain Divisio/is of the Szvifts. I I While retainin_i> the <j;cneral cliaract
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