286 ME. W. P. PYCRAFT ON THE MOEPHOLOGT AND 



Fig. 6. Ventral aspect of fig. 2, showing the broad vomer and its continuance 

 backwards on to the pterygoid. The palatines articulate with the external 

 border of the foot of the vomer and external border of the pterygoid. In 

 Rhea the articulation between pterygoid and vomer is concealed by the 

 palatine. 



Fig. 7. Ventral aspect of fig. 3, showing the vestigial vomer, which does not now 

 articulate with the pterygoid. Note the absence of the palatine processes of 

 the premaxillse. The palatine has fused with the external pterygoid border. 



Fig. 8. Ventral aspect of fig. 4, showing the complete fusion of the vomer, pterygoid, 

 and palatine. 



Additional Letters. 



ant.b.f.= anterior basi-cranial fontanelle. 

 ant.h. = antrum. 

 b.b.p.= basitemporal platform. 

 5.^. = basipterygoid processes. 

 hy.for. = hypoglossal foramina, 1, 2, 3. 

 /. = lachrymal. 

 Z.p. = lachry mo-nasal pillar. 

 l.r. = lambdoidal ridge. 

 m.e. = mesethmoid. 

 mx.p. = maxillo-palatine process. 

 n.pmoc. = nasal process of premaxilla. 



n. = nasal. 

 o.c. = occipital condyle. 

 joa. = palatine. 

 jofl.r. = par'asphenoidal rostrum. 

 p.pmx. = palatine process of premaxilla. 

 P-P- — paroccipital process. 

 pt. = pterygoid. 

 s. = supra-orbital bones from lachrymal to 



frontal. 

 v. — vomer. 

 vag.for. = vagus foramen. 



PLATE XLIII. 



The immature Skull. 



Fig. 1. Dorsal aspect of the palatine bones of Apteryx mantelli (p. 204), to show the 



sutures, as yet unclosed, between the vomer, pterygoid, and palatine. 

 Fig. 1 a. Ventral aspect of the same, to show similar sutures. 

 Fig. 2. Sagittal section of skull of Apteryx australis mantelli, after Parker, for the 



purpose of comparison with Dromwus. Note the appearance of the squamosal 



on the inside of the skull in Apteryx. 

 Fig. 3. Ventral aspect of the skull of Emeus (p. 270), for the purpose of comparison 



with Rhea. Note the similarity in the relations of the pterygoid and vomer. 

 Fig. 4. Sagittal section of cranium of embryo Dromwus novce-hollandke, to show the 



separate bones. 

 Fig. 4 a. Outer view of fig. 4. Note how completely the squamosal conceals and 



protects the pro- and opisthotic bones. In the nestling Penguin the 



squamosal is deeply emarginate posteriorly and exposes the otic bones. 

 Fig, 5. Ventral aspect of base of skull of Rhea americana, to show sutures. 



