PROFESSOR OWEN ON THE GENUS DINORNIS. 



349 



Breadth of the cranium across the mastoids (s, s) . . 

 Length of the cranium to tlie anterior border of 1 



the coalesced frontals (ii) i 



lireadth across the postorbital angles 



Hreailth across the temporal fossie 



Vertical diameter from supraoccipital ridge to basi- "I 



sphenoid | 



Transverse diameter of occipital foramen 



Breadth across the paroccipitals (a, t) 



Total length of skull, in a straight line 



Total length of premaxillary 



Breadth of base of upper beak at fore-part of frontah 



Breadth of the middle of the upper beak 



Breadth of the extremity of the upper beak 



From the fore-part of the external nostril to the f 



end of the beak f 



From the fore- part of the palatal nostrU to the end 1 



of the beak | 



Length of the palatal nostril 



Breadth of the palatal nostril at middle 



Palaptcryx 

 struthoides. 



inches, lines. 



3 3 



2 5 

 1 6 

 7 



Dinornis 

 casuariiius. 



inphes. line*. 



'2 9 



11 





 II 



6 

 11 

 2 

 3 

 3 

 1 

 6 



10 



4 



Palapterj'X 



gcranoides ? 



incbe«. lines. 



2 5 



10 

 9 



5i 

 10 



10 



1 



I'alaptcryx 

 dromioides. 



incbca. line*. 



2 7 



Gi 



The cranium of the Dinornis in its general broad and depressed form, in the pedun- 

 culate condyle, in the vertical plane of the foramen magnum (fig. 4, o), in the direction 

 from below upwards and forwards of the broad and low occipital surface (fig. 1, 3), in 

 the slight convexity of the parietal region (fig. 2, 7), and in the wide and deep temporal 

 fossae (fig. 1, t, 8", 12), repeats the characters exhibited by the previously described spe- 

 cimens of the cranium of Palapteryx (pp. 308-313, pis. 38 & 39). But some of these 

 cranial peculiarities of the great extinct wingless birds are exaggerated in the typical 

 genus, especially the downward development and abrupt descent of the basioccipital and 

 basisphenoid (fig. 4, s) and the forward inclination of the occipital surface, which makes 

 the occipital condyle (figs. 4 & 6, i) the centre of the hinder surface of the skull, and 

 places the occipital foramen (o) in the upper half— characters hitherto unknown in the 

 air-breathing Vertebrata; amongst which the Crocodilia, perhaps, present the nearest 

 approximation to the peculiar structure exhibited in fig. 4. 



The occipital condyle (i) is a hemispheric tubercle, impressed by a subcentral pit, 

 supported on a short thick peduncle, and projecting beyond the vertical line dropped 

 from the upper border of the foramen magnum. It presents a similar form in Otis 

 (fig. 8), but is sessile and overhung by the upper border of the foramen, as it is like- 

 wise in Didus, in which the condyle is a transverse reniform tubercle with a median 

 notch above. The basioccipital expands as it descends with a curve concave back- 

 wards ; but, passing into the basisphenoid which continues the descending surface 

 and inclines forwards, the curve becomes convex backwards, and thus describes a 

 sigmoid line in the vertical direction : the lateral borders of this broad subquadrate 

 occipito-sphenoidal plate (i", ,5', figs. 4 & 6) are bent backwards, making the whole 

 surface concave transversely. The upper portions of the lateral borders (i") form 



