284 PROF. OWEN ON THE ANATOMY 
supraorbital glands : the whole cranium also is much higher and shorter in proportion 
to its breadth than in the Apteryx. The Ibis, in thus differing from the Apteryz, deviates 
also from the other Struthionde. 
At the base of the skull we find in the Apteryw all the peculiarities characteristic of 
the Struthious birds. The body of the sphenoid sends outwards on each side two pro- 
cesses, of which the posterior abuts against the tympanic bone, and the anterior one, by 
a flattened oval articular surface against the pterygoid bone: the latter processes exist, 
but are much more feebly developed, in the Jbis: in most other birds, including the 
Gralle, they are wanting: they are well developed in the Lacertine Sauria. A com- 
pressed vomerine process is continued forwards from the anterior part of the basi- 
sphenoid, and this process is anchylosed to the under part of the expanded and cellular 
ethmoid. 
In the interior of the cranium the olfactory depressions are seen to be proportionally 
larger than in other birds, and the olfactory nerve, instead of being continued along the 
upper part of an interorbital septum by a bony canal or groove to the nasal cavity, 
immediately passes, by many perforations, through a cribriform plate to the complex 
and extensive pituitary surface of the ethmoid bone. 
The optic foramina are distinct both internally and externally, and are half an inch 
apart ; they are perforated, not in the sphenoid ala, but in the inflected margin of the 
frontal bone. In these peculiarities the Apterya differs from all the rest of its class: 
each optic foramen, however, transmits not only the optic nerve and ophthalmic artery, 
but also the third, fourth, first branch of the fifth, and sixth nerves, as in most other 
birds. Of these nerves the fifth is the largest, and it is continued forwards to the 
nasal canal, through two foramina, one circumscribed externally by the process already 
mentioned, which extends from the frontal to the ethmoid ; the other by the corre- 
sponding process of the lachrymal. The pituitary fossa, or sella turcica, is a very deep 
semi-oval depression ; the common internal orifice of the two carotid canals commu- 
nicates with its posterior part. On each side of the anterior part of the floor of the 
cranium, which supports the medulla oblongata, there is an oblique slightly curved 
groove, terminated at its anterior extremity by the foramen rotundum, at its posterior by 
the foramen ovale. These foramina are situated between the basilar and alar elements 
of the sphenoid ; they are nearly of equal size, and are relatively larger than in the di- 
urnal Struthionide. "The foramen rotundum is not only distinct, but is further apart 
from the foramen opticum than in any other bird. The petrous bone projects internally in 
the form of a thin semicircular plate of bone, commencing at the foramen ovale and ex- 
tending backwards to the foramen auditorium internum, which it overhangs: this plate 
gives attachment to the tentorium. There is not any corresponding bony ridge deve- 
loped from the upper wall of the cranium in the line of origin of the falx, as in many of 
the Gallinaceous birds. The anterior or cerebral division of the cranial cavity is larger 
in proportion to the posterior than :n most other birds. 
a 
