90 OSTEOLOGY [Parr II. 
border of the optic foramen; at its deepest part it presents the foramen ovale. The oculo-motor aperture 
opens within the posterior border of the optic foramen, beneath the orifice for the trochlearis nerve. The 
form of the cerebral fossee indicates that the cerebral lobes were broad and rounded in front, and elevated 
above the level of the cerebellum ; the mesial ridge dividing them is low and obtuse, and subsides anteriorly 
towards the inter-olfactory septum, which is slightly carmate vertically; the outer edge of the olfactory 
foramen is subacute. The broad platform, formed by the interorbital septum between the olfactory and 
optic outlets, is convex in both diameters ; its posterior, thick and rounded border projects over the groove 
lodging the optic chiasma. The surface of the cerebral fossa is smooth, and presents no trace of division 
into compartments. 
The strong, much compressed and elongated wpyper mandible, corresponding to the two anterior thirds 
of the cranium, may be regarded as forming a three-sided pyramid; whose base is bevelled off im a 
direction downwards and forwards ; the feebly uncinated apex projects beneath the level of the narrow 
palatine facet; and a plane replaces posteriorly the edge to which the broad lateral surfaces incline above. 
The thin upper margin of the base forms the hinge for the movements of the mandibular apparatus ; from 
its anterior and inferior angles pass backwards the palatine bones to meet on the sphenoidal rostrum, while 
the slender pterygoids form a counter arch, springing from the inner angle of the inferior articular surface 
of the tympanic on either side; its crown abuts against that of the palatine. The strong sigmoid zygoma 
ascends from the external and inferior angle of the tympanic, to the centre of the outer edge of the base. 
The length of the upper mandible, measured from the cramio-facial line, is five inches eight hnes, from the 
same line obliquely to the apex, five inches mine lines and a half; its greatest breadth is one ich seven 
lines; and its height, opposite the inferior angle, is one inch five lines and a half. 
The high, compressed core occupies the apical third; it is formed by the premaxillary, whose strong 
mesial process, with the ento-nasal plate on each side, constitutes the upper beam of the mandible, a faint 
linear impression indicating their respective boundaries; the narrow lanceolate nasal fissure, perforating 
the basal two-thirds, divides the upper from the compressed lateral stems. The sutures between their 
elements are wholly obliterated ; judging from analogy, the lateral process of the premaxillary bifurcates 
at a short distance behind the core, the inferior shp extendmg along the palatine surface, while the upper 
sinks into the outer aspect of the maxilla, and is wedged posteriorly between it and the expanded foot of 
the ecto-nasal Lmb, whose inferior boundary would probably be indicated by a ine about an inch in 
length, drawn from the malar process to the lower border of the nasal fissure; along the posterior half of 
this line it meets the maxilla, which then passes internally to near the core, and forms the upper and lower, 
thick and rounded borders of the lateral beam, except for a short space anteriorly. 
The lateral stem thus constituted has an elongated subtriangular form, with the truncated apex 
towards the core ; the upper subconcave margin is three inches nine lines long; the base of two inches 
and three lines, ascends obliquely backwards, forming an angle of 125° with the palatine edge, which is of 
equal length. Viewed from above, the mandible presents a broad shallow excavation, impressing the outer 
surface of the lateral beam on each side, and extending from its prominent external basal edge, behind 
which the mandible is flatly compressed, forwards to the core. 
This peculiarity in the skull of the Dodo, is due to the close approximation of the lateral stems 
in their anterior half; the mandible being most constricted about an inch behind the core, where its 
breadth is only seven lines, and its height one inch and three lines. The least breadth of each stem at 
the same place is three lines and one-third, and from this point they become rather broader as they proceed — 
forwards, their lateral surfaces curving outwards to pass into those of the core; posteriorly they diverge 
