352 PROFESSOR OWEN ON THE GENUS DINORNIS. 
orbit, occupying the anterior part of the interorbital space, joining each other at the 
median line by an extensive vertical cellular surface, and dividing the orbital from the 
rhinal cavities. In Apteryxr and Dinornis the latter cavities are so developed as to 
extend backward between the orbits to the cranium, the front wall of which forms the 
back wall of the rhinal instead of the orbital cavities. 
The temporal fossa (Pls. LIII., LIV., LV. 7’) is divided by the pretympanic ridge and 
process of the mastoi d 8") into a posterior compartment (PI. LV. fig. 1, 8) for the pos- 
terior ‘temporalis’ muscle, of a triangular shape, 10 lines broad at the upper part, and 
an anterior larger and deeper depression (ib. 7’), rounded above, 1 inch 5 lines in 
breadth, and bounded anteriorly by the broad, triangular, vertically descending post- 
frontal (ib. 12). These temporal fossz, as in the less perfect skull (PI. LIII. fig. 1, 7), 
are nearly 2 inches apart on the broad, flattened upper surface of the cranium (7), 
where the boundary-ridge is scarcely, if at all, defined. 
The orbit (Pl. LV. 0) is smaller in proportion to the size of the skull than in most 
birds, but is much better defined than in the nocturnal Apteryx. The bony boundary 
is formed posteriorly by the convex border of the postfrontal (12'), above and in front 
of this by the thin superorbital part of the frontal, which is gently wavy ; it then curves 
down as a thicker triangular process (a) to form the fore part of the orbital frame. 
The inner surface of this process developes a low vertical ridge, in part articulated with 
the outer portion of the rhinal cincture ; and the lower part of this ridge is pierced by 
the lacrymal foramen, indicating the process to be a lacrymal (ib. 73) confluent with the 
frontal and prefrontal. 
The nasal is, in like manner, confluent by its upper border (PI. LIII. fig. 1, Pl. LVI. 
fig. 3, 15) with the frontal, its outer descending maxillary process (PI. LV. fig. 1, Pl. LVI. 
fig. 3, 15’) terminating freely by a slight expansion which rests upon the maxillary 
(Pl. LV. fig. 1, 21). The premaxillary process of the nasal (15) is broad and flat, sup- 
ported by the prefrontal expanse (Pl. LVI. fig. 3,14); it is in great part excavated 
above by the shallow rough depression for the premaxillary stem (Pl. LIII. fig. 1, 22’), 
and shows a narrow, thickened, and smooth tract bounding that depression externally 
or laterally. 
The plane of the orbital cavity, so far as it is formed by bone, is directed from 
behind obliquely forward and upward at an angle of 45° with the axis of the skull, the 
eyes thus being directed more forward and downward than in birds generally. The 
downward cast of the eyes relates to the great height of the Dinornis, and the 
position of its food upon the ground. The roof of the orbit shows an oblong shallow 
depression at its back part for the Harderian gland, and a deeper anterior pit for the 
lacrymal gland. The fore part of the maxillary (Pl. LVI. fig. 1, 21’) is an oblong, bony, 
pneumatic capsule, 2 inches in length and 1 inch 3 lines in breadth, flattened below, 
where the surface is equally divided between the sutural part underlapped by the 
maxillo-palatal part of the premaxillary (22”) and the free, smooth surface, extending 
