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elevation of the superoccipitals, it reaches the level of the upper surface of the cranium, 
owing to the flatness of the parietals: it slopes forwards at once from the upper border 
of the foramen magnum. The broad paroccipitals (4) spread outwards and backwards, 
and nearly attain the level of the upper surface of the cranium. 
Each parietal terminates behind in an obtuse angle, which penetrates a corresponding 
emargination in the superoccipital near its outer angle; and it sends a rounded pro- 
jection from its anterior border, near its outer angle, which enters a corresponding 
emargination between the frontal and postfrontal. The outer part of the parietal 
bends down, forms the bottom of the temporal fossa, and meets the alisphenoid near 
the lower part of that fossa at a straight longitudinal suture. The tumid mastoid (8) 
forms the outer and posterior angle of the upper surface of the skull, as in the Crocodile, 
and is wedged between the parietal, superoccipital, alisphenoid, and tympanic bones, 
for which latter bone it affords the major part of the glenoid cavity, The apophysary 
part (8’) of the mastoid descends vertically from its outer side for more than half an 
inch, external and posterior to the tympanic; the inner side of the base of the process is 
perforated by the pneumatic foramen supplying air to the cancelli of the cranial walls. 
In consequence of the non-obliteration of the sutures in the young bird, to which this 
interesting cranial fragment has belonged, the right mastoid had become detached, ex- 
posing the great breadth of its suture with the parietal and alisphenoid ; and the pneu- 
matic foramen is exposed. The whole extent of the paroccipital process is preserved 
on this side. The loss of the frontals and orbitosphenoids from the fragment of skull 
in question shows the thickness of the cranial walls at the coronal suture (2b. fig. 3, r), 
and exposes the cranial cavity, which is here divided into epencephalic, mesencephalic, 
and prosencephalic chambers. The epencephalic division is entire, is excavated below 
for the medulla oblongata, and above for the cerebellum, and is perforated behind by 
the foramen magnum (fm). The mesencephalic division (9) consists of two small, 
well-defined, hemispheric pits for the optic lobes, in front of the lower part of the 
epencephalic chamber. ‘The portion of the prosencephalic division (p) above and ex- 
ternal to the depressions for the optic lobes is excavated in the alisphenoids and 
parietals: the thick cancellous walls form a striking contrast to the general character 
of the cranial parietes in birds. The deep subspherical sella turcica (2) sinks down 
between the mesencephalic pits. 
As compared with the cranium of other birds, and particularly with those of the 
Ostrich and Emeu, the Dinornis and Palapteryx are remarkable for the forward produc- 
tion and lateral expansion of the upper cranial walls. In the Ostrich, a vertical line 
dropped from the point of union of the sagittal with the coronal sutures, would fall into 
the interspace between the basioccipital and basisphenoid: in the Emeu the same line 
falls behind the sella turcica; but in the Dinornis, the same line falls in advance of the 
sella turcica, In taking the greatest vertical diameter of the cranium of the Ostrich, 
the points of the compass touch the middle of the frontal region, and the interspace be- 
