1906.] OF THE TRACHEOPHOXE 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 Pipridfe agree with the Cotingidae, and should probably be in- 

 cluded therewith ; and the Cotingidfe in turn agree in this point 

 with the Eurylsemidse. There is an incipient nasal hinge in the 

 Pittid^. 



The Base of the Skull. 



Basipterygoid processes are absent. The basitemporal plate, 

 except in Pittida?, 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 anteiiorly, 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 Asj^ect of the Craniimi. 



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. 



The superior tympanic recess opens in the Conojoophagidfe, 

 Pipridfe, Dendrocolaptinfe, and Synallaxinee 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 

 poste?'ior. In the Pittidfe, Philepittidfe, Conopophagida?, and 

 Formicariinee these two apertures are separated by a long bar. 

 The fenestral recess opens at the end of the bony column dividing 

 the antei-ior and postei'ior tympanic recesses. 



The periphery of the tympanic recess presents characters of 

 sufficient interest to deserve a brief survey. 



In the Pittidfe, Oonopophagidse, Formica riidfe, and Dendro- 

 colaptinse the free edge of the lateral occipital wing rises upwards 

 and forwards to pass into a large depressed pn^ocessus 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 fi-ee end of a more or less well-marked processus 

 articularis squamosi. In the Synallaxinas and the Conopophagidfe, 



