Cu. I.] OF THE DODO. 79 
processes, is one inch six lines and a half; and its depth from the upper margin of the foramen magnum, 
ten lines and a half; from the mesial line obliquely to the angle of the paroccipital process, is one inch 
two lines. The longitudinal diameter of the inferior segment is eleven lines and two-thirds; and the 
span of its lateral boundary is eight lines and a half. The span of the anterior margin between the apices 
of the basilar protuberances, is eight lines and a half. The basi-occipital is three lines and a half thick. 
The inferior facet of the cranium exhibits, on each side, the great orbito-temporal excavation, separated 
by the short but broad and tumid sphenoid, which expands to join the basi-occipital posteriorly ; it is most 
constricted at the junction of its posterior and two anterior thirds, opposite the foramen opticum ; it 
increases in breadth, as it advances, to where it is jomed by the imferior ethmoidal ala on each side; it then 
rapidly becomes narrower, and forms a compressed plate projecting forwards into the inferior nasal fissure. 
The inflated lower ala of the ethmoid coalesces externally with the bullose inferior extremity of the 
prefrontal ; which, from the compression of the cranium anteriorly, is prolonged forwards ; a deep narrow 
notch, leading into the olfactory fossa, separating it from the rostrum. The greatest width of the sphenoid, 
between the outer margins of the tympanic tubes, is one inch, eleven lines and a half; its extreme length 
is two inches, six lines and a half; where most constricted it is six lines and two thirds broad. The distance 
between the outer surfaces of the inferior extremities of the prefrontals amounts to one inch, eight lines 
and a half; the thickness of the sphenoid at the foramen opticum is four lines and a half. 
The lozenge-shaped concavity on the sphenoid, for the insertion of the fleshy fascicuh of the Rect: 
capitis antici muscles, is deepened posteriorly and laterally by the anterior surface of the basilar protu- 
berance, which is directed, on each side, inwards and backwards, sloping outwards as it descends to the 
apex ; anteriorly and laterally a slight ridge separates it from a venous impression on the side of the 
sphenoid. The anterior angle projects in the form of a small, free, triangular plate, curving downwards 
beneath the transversely ovate common orifice of the Hustachian tubes; the posterior corresponds to the 
median notch between the inner angles of the basilar protuberances. This surface is distinctly pitted on 
each side of an irregular raphe: and its antero-posterior diameter is eight lines. 
A groove, two lines broad, running forwards from the orifice of the Eustachian tubes, impresses the 
sphenoid where most constricted, and ceases after a course of four lines with a rounded termination ; its 
edges are sharp, and separate it from the lateral venous impressions ; it is lined by the sinus leading to the 
Eustachian tubes. 
Anteriorly the sphenoid is raised into an obtuse median ridge, between the flattened oblong surfaces 
on which the palatine and pterygoid bones glide, in the movements of the upper mandible. 
The inferior aspect is concave upwards, deepest opposite the foramen opticum, declinmg in front to 
the lowest part of the rostrum, and behind to the under surface of the occipital condyle, which is im the 
same horizontal plane as the former. 
The dateral aspect of the cranium is occupied by the large orbito-temporal fossa, which presents the 
form of an irregular, four-sided pyramidal excavation ; the floor and inferior wall of which are removed. 
Its different surfaces converge to the optic foramen ; the posterior is of less height than the anterior, the 
upper descending as it retrogrades. 
The anterior subconcave wall, is formed in its anterior moiety by the prefrontal, and by the united 
turbinated and inferior ale of the ethmoid; posteriorly it is constituted by the enormously thick, but con- 
tracted, interorbital septum ; it slopes gradually inwards and backwards, and above is rounded off into the 
roof of the orbit. A line drawn from the post-orbital process to the optic foramen, divides the orbital from 
the narrow, depressed temporal fossa, which inclines forwards, as it descends inwards. The posterior trian- 
¥ 
