32 MR. W. p. PYCRAFT ON THE \]^^J 2, 



the base of the beak it expands considerably and is supported from 

 within by outstanding antorbital plates. Lachr^anals, except in 

 Galyptomena, are absent, and consequently take no share in the 

 formation of the preorbital i-egion of the skull. In this particular 

 the Euryl8emid?e agree with the bulk of the Passeres, in which, 

 however, vestiges of the lachrymal are frequently present. 



The frontals terminate abruptly in front, not extending beyond 

 the level of the anterior border of the mesethmoid. The nasals 

 and nasal-processes of the premaxilla are also sharply truncated 

 cauclad ; thus, at their meeting with the frontals and mesethmoid 

 a freely moving nasal hinge is formed (PI. II. figs. 2 &, 3 a, 4). 

 The incipient stages in the development of such a hinge can be 

 studied in Chasmorhynchus — one of the Cotingida?. 



The Base of the Skull. 



The basitemporal plate is slightly hollowed in the middle line, 

 and is continued forward for some distance on to the parasphenoidal 

 rostrum ; owing to the small size of the brain its free edge 

 projects beyond the level of the brain-case. To appreciate this 

 point the skull of one of the Eurylfemidse should be compared 

 with say that of Menura or Corvus, where, it will be found, the 

 basitemporal plate fails to conceal the brain-case when the skull is 

 seen from below. The edge of this plate is free only at its apex. 



JSTot even vestiges of the basipterygoid processes remain. 



The parasphenoidal rostrum is long and slender. 



The occij^ital condyle is spherical and depends from the roof of 

 a shallow pre -condylar fossa. 



The Lateral Asjyect of the Cranium. (PI. II. fig. 2.) 



The tympanic cavity is small, shallow, and has little oi' no floor. 

 The constriction of the skull-wall in the temporal region, to form 

 the " temporal fossse," gives the tympanic cavity the appearance of 

 the aperture of a tube, the cylinder of which is formed by the 

 "squamosal pi'ominence" and lateral occipital wing. 



The roof of this cavity is formed by the under surface of the 

 processus zygomaticus squamosi. Its floor in part by the lateral 

 occipital wing and in part by the ossification of tissue extending 

 between this wing and the external angles of the basitemporal 

 plate ; but this region is much cut away. 



Within the cavity three apertures will be found in the dried 

 skull after the removal of the tympanic membrane. The largest 

 of these is the mouth of the recessus tympanicus anterior. 

 Immediately outside this, and below the otic articular surface for 

 the quadrate, is the fenestral recess : this is very small, and neither 

 the fenestra ovale nor the rotunda can be distinguished within it, 

 though the columella is in position above ; and behind the fenestral 

 recess a cluster of minute j^i^eumatic apertures will be found, 

 corresponding to a similar group commonly found in the higher 



