PROFESSOR OWEN ON THE GENUS DINORNIS. 357 
They are wholly anterior to the cerebral cavity. Their condition in Aptornis otidiformis 
(Trans. Zool. Soc. vol. iii. pl. 52. fig. 5, 18) is closely repeated in Apt. defossor. 
The cranial ‘cavity, exposed in the present specimen by an opening on the left side 
(which may have been made to extract the brain), shows a slight falcial ridge; and 
about half an inch outside this, runs a less marked parallel ridge, indicative of a longi- 
tudinal sulcus on the surface of the cerebral hemisphere. The under parts of the 
anterior cerebral lobes were divided from each other by a short ridge continued forward 
from above the common intracranial beginning of the optic foramina. A well-marked 
curved “tentorial” ridge marks the boundary between the prosencephalic and the 
combined mes- and ep-encephalic divisions of the cranial cavity. The “sella” is small 
and moderately deep. There is a well-defined, oblong, rough depression for the 
“ Harderian gland ” at the back part of the orbit. 
The nasal bones (Pl. XL. figs. 1 & 2,15) seem to touch each other at their postero- 
internal angles, whence they diverge, and are distinct from each other in the rest of 
their course. ‘They coalesce with the frontal; but the fronto-nasal suture seems trace- 
able, forming a strong curve convex backward, touching the transverse parallel of the 
middle of the superorbital ridge, and thence curving forward to the antorbital process, 
where a portion of the suture is persistent: it is possible that this curved line may 
indicate the limit of a frontal expanse of the nasal. At one inch and a quarter from 
the hindmost part of the nasal, that bone bifurcates into its maxillary (b) and pre- 
maxillary (a) branches. 
The maxillary branch (Pl. XL. fig. 1,4) is a long, straight, narrow, subdepressed rod, 
a little wider midway, and coalescing with the nasal process of the maxillary (ib. 21) too 
closely for any trace of the original distinction. 
Although the nasal branch of the premaxillary (22) has coalesced with the nasals, the 
line of original distinction is traceable, and shows the premaxillary branch of each nasal 
(ib. fig. 1, a) to have become soon overlapped by the premaxillary, and to have extended 
forward from the bifurcation of the nasal nearly two inches, each slightly inclining 
toward its fellow, underlapping and strengthening that part of the bony arch of the 
upper mandible. 
The palatine plate of the maxillary (Pl. XL. fig. 3, 21’) underlaps that of the pre- 
maxillary ( 22" ), filling the interval between it and the dentary part of the premaxillary. 
The line of suture is apparent; it is transverse and convex forward, nearly in the same 
relative position to the prepalatine vacuity as in Vinornis'. This vacuity is continued 
backward between the maxillaries (ib. 21’), and then between the palatines (ib. 20), and is 
continuous with the palato-nares (ib. e, é). 
‘The palatines (20), at their upper and mesial beginnings, extend backward, parallel to 
each other, for an inch or more on each side of the vomer and the fore end of the pre- 
sphenoid. Their contiguous sides in this extent are nearly straight, with an interval of 
1 See Dinornis ingens, Trans. Zool. Soc. vol. vii. pl. 15. fig. 3, 22”, 21, 
