134 PROFESSOR OWEN ON THE GENUS DINORNIS. 
Both nasals and frontals were unfortunately wanting in that instructive portion of 
the cranium of the young Gigantic Dinornis figured in the ‘ Zoological Transactions,’ 
vol. iy. 1850, pl. 24. figs. 1, 2, 3. I have found the nasal confluent with the frontals 
in all other specimens of skulls of more or less adult birds; they are planed off, as it 
were, above, to let in the nasal process of the premaxillary. Such depressed articular 
surface (Pl. XII. fig. 8, 15) does not reach further back than the transverse parallel of 
the lachrymal part of the orbits. 
The prosencephalic part of the cranial cavity makes a prominence above the general 
level of the calvarium, The postfrontal (ib. fig. 1, 12) is nearly vertical. The temporal 
fossa is narrow antero-posteriorly compared with that in Dinornis elephantopus, but is 
relatively wider than in D. crassus: a postcrotaphyte fossa is defined by a short, pre- 
mastoid, pointed process’. The mastoid process (fig. 1,8) is long, subcompressed from 
before backward, and pointed. 
The rostral part of the premaxillary (ib. 22) is relatively longer than in D. crassus or 
D. elephantopus, shorter than in D. robustus; it is minutely perforated, showing a cork- 
like surface; that of the nasal process (22’) resumes the usual smoothness, as does the 
premaxillary part of the internarial septum (s). The premaxillary is more suddenly 
pinched in, as it were, laterally, to form this septum, than in any of the above species ; 
its fore-and-aft extent is two-fifths that of the premaxillary prior to its trifurcation. The 
entire portion of the bone forming the end of the upper mandible is slightly deflected, 
and terminates subacutely. The upper median tract is defined by a well-marked, 
though shallow and narrow, groove on each side, ending about four lines from the apex. 
The palatal surface shows a low, narrow or linear median ridge, and two wider marginal 
or alveolar grooves; between these grooves the surface is transversely concave at the 
middle, and convex on each side. At about an inch from the apex the mid ridge sub- 
sides, and the bifurcation of the palato-maxillary processes begins; the fissure is rela- 
tively longer and narrower than in Dinornis robustus. ‘The narrow base, or beginning, 
of the nasal process (fig. 1, 22) shows a linear mid furrow on its upper surface, which 
disappears as the process flattens and expands; the under surface of the process shows 
a low mid ridge, against which the margins seem to be bent or folded inward to form 
the front part of the internarial septum. The hind free concave margin of this septum 
shows the fissure left between the inflected lamine, which diverge below to form the 
upper surface or layer of the palatal part of the premaxillary. At the place of diver- 
gence, above the lower palatal layer, are the mid fossa and two lateral nervo-vascular 
canals conveying the trunks of the many ramifications which emerge at the perforations 
of the cork-like outer surface to constitute (or help thereto) the periosteal formative 
bed of the upper horny mandible. 
The maxillary is broadest anteriorly, where it sends inward from its lower part the 
‘ The homologue of the ridge bisecting the temporal fossa, and produced beyond the ordinary mastoid in 
Aptornis (Trans. Zool. Soe, vol. iii. pl. 52. figs. 1, 8’). 
