211 
The skull, of which a vertical section is figured in Pl. LIII. fig. 4, appears to belong to 
the same species as that figured in Pl. XLVI. fig. 5, and differs from those figured in 
Pl. LIII. figs. 5 & 6 in the minor development of the mastoid and postfrontal processes. 
The olfactory chambers (is) are deep, and the diameter of the single orifice penetrating 
the upper and back part of the roof of each division of that cavity, indicates the large 
size of the olfactory nerve. The outer and inner tables of the cranium are seen to be 
divided by a diploé of air-cells about one and a half line thick ; but the extent of the 
diploé varies much when seen in transverse section. 
The epencephalic chamber (a, v, c) is remarkable for its size, rising to the highest level 
of the prosencephalic one (p), and sinking much below it; the mesencephalic fossa (0) 
is comparatively small. The transverse section across the broadest part of the cranium 
shows that the prosencephalic cavity is far from being of corresponding breadth: a 
considerable extent of diploé intervenes between that chamber and the base of the 
postfrontal processes. The outer and inner tables unite without diploé above the 
highest part of the upper longitudinal elevations of the cerebrum. The inner circum- 
ference of the olfactory orifices is partially grooved. 
In order to gain some idea of the size of the bird to which the largest cranium 
belongs, I have compared the diameter of its foramen magnum with that of a lower 
cervical vertebra and of a middle dorsal vertebra, both referable by their size to the 
Dinornis giganteus, the same comparisons having previously been made in the skeleton 
of the Ostrich. 
Dinornis. Ostrich. 
Lines. Lines. 
Transverse diameter of the foramen magnum. . altar ss Sg 65 
Transverse diameter of middle of spinal canal, lower pesiacal: vertebra. 63 5 
Transverse diameter of middle of spinal canal, dorsal vertebra . . . . 7 45 
From the above admeasurements and comparison we might be led to conclude that 
the skull of the Dinornis yielding that of the foramen magnum belonged to a larger 
species than the vertebre ; but the size of these vertebrz forbids the supposition ; for 
they are larger in proportion to the size of the skull compared, than in the Ostrich. 
The canal for the spinal chord is, in fact, singularly small in proportion to the bulk of 
the entire vertebra in Dinornis as compared with that in the Ostrich or other birds, 
and forms, as has been pointed out at p. 99, one of the peculiarities of the large 
wingless birds of New Zealand. The cervical vertebra, for example, with a spinal 
canal six and a half lines wide, has a body of four inches in length; whilst that of the 
Ostrich with a spinal canal five lines in diameter has a body only two and a quarter 
inches in length; and the dorsal vertebra presents similar relations. 
Lower jaw.—An almost entire lower jaw of a Dinornis or Palapterya, of rather smaller 
size than the one of which a large portion is figured in Pl. XLV. figs. 6, 7, closely 
accords with that portion as far as they can be compared: the symphysial end of the 
