36 MR. W. p. PYCRAFT ON" THE [May 2, 



Corydon, Eurylmmus, and Gymhirhynchus diifer conspicuously 

 from Calyj)tomena in this matter of the nai-ial aperture, as may be 

 seen by a comparison of figs. 2 5, 3 a, 4, PI. II. 



In all three genera the nasal is reduced to its smallest possible 

 limits, little more than an arcuate bar being left. Of this, one 

 half represents the descending process of the nasal, the other the 

 body of the bone, — now merely a rod joined at its inner end to 

 the nasal process of the premaxilla, and affording the means of 

 articulation with the frontals. This, as I have remarked, takes 

 the form of a nasal hinge. In Eu.ryloi'nmis and Corydon the nasal 

 fossa, as in Gcdyptomena, is open in the dried skull, the actual 

 position of the nasal orifice in the living bird being indicated by 

 semicircular grooves in the anterior border of the nasal fossa. 

 The circle completing the rest of the fossa in the living bird 

 was roofed by the alinasal wall. In Gymhirhynchus this wall 

 almost completely ossifies, leaving an oval narial aperture, and 

 a small semilunar space immediately in front of the nasal (fig. 3, 

 PI. II.). 



In the Eurylfemida3 the floor of the olfactory chamber is open 

 behind, revealing in Galyj^tomena an ossified sheet-like nasal 

 septum, which in Goryd.on becomes immensely swollen. 



In the Ooracise, certain Caprimulgi and Pici the floor of the 

 olfactory chamber is more or less ossified. In Eurystomits and 

 the Bucconidse there is a long palatal fissure, which at first sight 

 appears to correspond to the huge palatal cavity of Ettrylceinus. 

 An examination shows, however, that this vacuity leads into a 

 spacious cavity underlying the olfactory chamber and formed by 

 the inflation and absorption of tissue of the nasal septum. In 

 Podargus the palatal surface of the prema.xilla is completely 

 ossified, and the olfactoiy chamber is reduced to the smallest 

 possible limits. 



In Gorydon the nasal process of the premaxilla is immensely 

 swollen and rises far above the level of the nasal hinge. The 

 frontal is similarly swollen immediately above this hinge. The 

 intermediate stages between this condition and that found in 

 Ccdyptomena can be studied in Gymhirhynchus. Gorydon, indeed, 

 would appear to have i^eached the high- water mark of speciali- 

 sation in the matter of the jaws, among the Euryleemidae. 



The Maxillo-jugal Arch. 



The maxilla, as usual, is in the adult completely fused with the 

 premaxilla. In Gorydon the maxillary region of the jaw is highly 

 developed and forms a large semicircular plate, the convexity 

 forming its fi'ee edge and projecting downwards far beyond the 

 level of the quadrato-jugal bar. 



The maxiUo-2ndatine 2^rocesses in Galyptotnena take the form of 

 a pair of delicate rods projecting backwards at a, very mai-ked 

 angle from the body of the maxilla, which, at this point, is 

 perforated by small pneumatic apertures. These rods, on each 



