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Show 1906.] OF THE TRACHEOPHONE PASSERES. 137 Pipra, where they are abruptly truncated to form, with the beak, a nasal hinge. In this, as indeed in all other characters of the skull, the Piprida? agree with the Cotingida?, and should probably be included therewith ; and the Cotingida? in turn agree in this point with the Eurylaemidae. There is an incipient nasal hinge in the Pittida?. The Base of the Skull. Ba si pterygoid processes are absent. The basi temporal plate, except in Pittidse, is somewhat swollen, and does not extend forward on to the parasphenoidal rostrum, but is bounded by a gently curved or slightly pointed anterior border, the edge of which has fused with the rostrum, leaving apertures for the Eustachian tube. In Pitta this plate is slightly concave, pointed anteriorly, and has a free edge. Xiphorhynchus appears to be unique, in that from the anterior border of the basitemporal plate just ventrad of the position usually occupied by the basipterygoid processes it exhibits a pair of long needle-like splints of bone immediately under the pterygoid and extending some distance beyond them, almost, in fact, reaching the long spine-like spurs of the palatines (transpalatines, Parker). Only in Pseudosisura (Homorus) is there any vestige of similar processes, and these take the form of minute prickles. The occipital condyle is very small, spherical, looks downwards and backwards, and lies within a deep precondylar fossa. The Lateral Aspect of the Cranium. The tympanic cavity is small and bounded above by the base of a more or less well-developed processus articularis squamosi, behind by the lateral occipital wing, and below by the external free edge of the basitemporal plate, while in front it is shut in by the quadrate. Of the usual apertures to be found within this cavity the recessus tympanicus anterior is the largest. Tlte superior tympanic recess opens in the Oonopophagidse, Piprida?, Dendrocolaptina?, and Synallaxina? by a moderately large aperture between the otic and squamosal heads of the quadrate; while within the lower segment of this aperture there will be found a cribriform plate leading into the recessus tympanicus posterior. In the Pittida?, Philepittidse, Oonopophagidse, and Formicariinse these two apertures are separated by a long bar. The fenestral recess opens at the end of the bony column dividing the anterior and posterior tympanic recesses. The periphery of the tympanic recess presents characters of sufficient interest to deserve a brief survey. In the Pittida?, Conopophagida?, Formicariida?, and Dendrocolaptina? the free edge of the lateral occipital wing rises upwards and forwards to pass into a large depressed processus zygomaticus squamosi, and is continued downwards, forwards, and upwards to form a bony wall apposed to the shaft of the quadrate and terminating at the free end of a more or less well-marked processus articularis squamosi. In the Synallaxina? and the Conopophagida?, |