266 
the prenarial septum (ib. fig. 1, s), from the free margin of which to the tip of the beak 
measures 1 inch 7 lines. 
The rough punctate surface sheathed by the horny bill passes rather gradually behind 
into the smooth septal plate. The maxillary branches (ib. figs. 1, 6, 22”) diverge back- 
ward at a more acute angle than in Dinornis robustus. The alveolar channel (ib. fig. 7) 
is much narrower; the intervening palatal tract is slightly concave without the median 
ridge, From the tip to the palatal fissure measures, in one specimen, 1 inch 5 lines; 
from the tip to the end of the maxillary process is 2 inches 5 lines; the breadth of the 
palate there is 1 inch 72 lines. 
The symphysial or rostral end of the lower jaw (ib. figs. 8 & 9) agrees with its homo- 
type aboye in its smaller size, more slender and pointed proportions, as compared with 
that in D. robustus. The outer median tract defined by the parallel grooves (fig. 8) is 
10 lines in length by 3 or 33 lines in breadth. The upper or inner smooth surface of 
the symphysis (fig. 9) is deeper as well as narrower than in D. robustus. 
Of the constituent elements of the mandible, the fore part of the splenial and the 
hind branches of the dentary retain their distinctness; the rest are welded together 
with the usual indications of the longitudinal fissure and foramina of the primitive 
separation. 
The articular expansion of the mandible presents a narrow outer articular tract rising 
longitudinally into an open angle, and a broader inner and anterior surface, deeply 
concaye transversely, almost level from before backwards, forming the anterior half of 
the digital cavity or depression, the posterior half of which is non-articular, and, in one 
specimen, is perforated by a small pneumatic foramen. ‘The angle of the jaw is 
obtusely rounded, and from it arise, diverging upon the back part of the ramus, two 
obtuse ridges bounding a shallow transverse concavity; the outer ridge is most pro- 
duced, especially at its termination. 
The mandible, in proportion to the cranium, is relatively shorter, and of less vertical 
thickness than in D. robustus. 
Skull of Dinornis crassus. (Plate LX XVI.) 
In the extensive collection of dinornithic remains from Ruamoa, Middle Island, pur- 
chased of Mr. Walter Mantell' in 1846 by the Trustees of the British Museum, were 
many skulls which could only be approximatively referred to their respective species 
according, to characters of size and proportion; and it was not until my reconstruction 
of the skeleton of D. elephantopus, described in vol, iy. of Trans. Zool. Soc. p. 159, that, 
besides the skull fitting the atlantal cup of the vertebral column of that skeleton, and 
apparently of the same individual, I could refer three other specimens’ of more or less 
mutilated crania, giving materials for the foregoing description, to the same species, 
Other skulls, next in inferiority of size, seemed probably from their number to belong 
' Ante, p. 234, * Nos, 32200, 32202, 32205 of the * Register,’ Geological Department, British Museum. 


