B98 PEOr. T. JEITEKT PAEKEE ON THE CEANIAL OSTEOLOGY, 



g. The Ilyoid. 



In the skull of Emeus, species a, figured on Plate LVI., the posterior cornua of the 

 hyoid — probably the only ossified parts — are present, as well as the larynx and anterior 

 end of the trachea. They consist of gently curved rods of bone, 57 mm. long, 2 mm. 

 in diameter, and expanded at both ends. 



Mr. Booth, who found this skull, told Professor Hutton that he saw in the ear a 

 delicate hair-like bone which he was unable to preserve; no doubt this was the 

 columella auris. 



4. A Comparison of the Skulls op the Dinornithid^ with those 



OP the other Ratit^. 



The occipital region is usually less clearly marked off from the skull in the other Eatitse, 

 the lambdoidal ridge being comparatively faint : the fully adult Apteryx australis forms, 

 however, an exception ; in it the lambdoidal ridge is very strongly marked, and there is 

 a distinct angulation between the roof and the hinder wall of the cranium. There 

 is no indication of the anterior lambdoidal ridge, and although the median occipital 

 region is swollen over the cerebellar fossa, the occipital crest is generally poorly 

 developed or absent; it is most distinct in Apteryx australis. The supraforaminal ridge is 

 obvious in all, and is continued to the angle of the paroccipital process; in Apteryx it 

 is interrupted, just at the margin of the foramen magnum, by a notch. Apteryx is the 

 only genus which resembles the Moas in its pedunculate occipital condyle, as also in 

 the great breadth — in relation to height — of the entire occipital region. In having 

 the plane of the occipital foramen vertical or nearly so the Dinornithidse stand alone. 



The roof of the cranium is more rounded in the other Ratitse, and in all but Apteryx 

 and Casuarius the parietal region slopes backwards instead of being nearly flat. As a 

 consequence of this, the temporal fossa has a much stronger backward inclination in 

 Struthio, Shea, and Dromceus, and the postorbital process is nearly in the same trans- 

 verse plane as the zygomatic instead of being well in advance of it. In this respect the 

 Cassowary approaches very closely to the Moas. 



Another very marked difference in the roof of the cranium is due to the relatively 

 small size of the eyes in the Dinornithidae. In the Ostrich, Emu, and Rhea, the 

 width of the orbit from the postfrontal process to the lacrymal is about equal to the 

 width of the cranium at the paroccipital processes ; in Casuarius galeatus it is about four- 

 fifths of the width, in the Moas not much more than half. Moreover, the interorbital 

 region of the skull-roof in the Ostrich, Rhea, Emu, and Cassowary is narrow, while its 

 preorbital region broadens out suddenly owing to the presence of large wing-like 

 orbital processes to the lacrymals. In the Moas this projection is only represented by 

 the comparatively small body of the lacrymal. In AjJteryx there are no post or pre- 

 orbital processes, and the skull-roof narrows gradually from the occipital to the nasal 



