OSTEOLOGY OF THE DODO. 77 
of the prosencephalic roof resembles that in Didus. The tentorial ridge bifurcates half 
way down, the front portion dividing, almost horizontally, the pros- from the mesen- 
cephalic compartment, the hinder and more obtuse ridge dividing, almost vertically, 
the mes- from the epencephalic compartment. The angle of bifurcation is slightly 
produced and obtuse, but represents very feebly the tentorial tuberosity (Pl. XXIII. 
fig. 1, 0) in the Dodo: from it, in Gowra, is continued backward the arch of bone formed 
by the superior semicircular canal, above which is the groove for the venous sinus, as 
in Didus. The internal auditory fossa is less deep than in Didus: above it is a similarly 
vertically oblong cerebellar pit. The nerve-foramina correspond with those in Didus: 
the entocarotid canal opens into a rather deeper sella in Columba palumbus. 
On comparing the cranial cavity, as exposed by a vertical longitudinal section in the 
Dodo (Pl. XXIII. fig. 1), with that of a Dinornis similarly exposed’, the first difference 
is the smaller proportional depth of the diploé in the larger wingless bird, which is not 
greater over the prosencephalic than over the epencephalic compartment; next may be 
noticed the larger relative size of the former compartment, indicating the larger cere- 
brum of the Dinornis, then the absence of the tentorial tuberosity, the sharper and 
more produced superior part of the tentorial ridge arching transversely between the 
cerebrum and cerebellum, the smaller internal auditory fossa, and the deeper sella: the 
mesencephalic compartment, or cavity for the optic lobe, is less in proportion to the 
prosencephalic compartment than in Didus; it holds, however, a similar relative posi- 
tion: finally, the cerebellar pit, above the internal auditory fossa, is wanting in the 
Dinornis. 
The Dodo agrees with the Doves in possessing a slender furculum, forming an acute 
angle; it resembles Columba galeata, more especially, in the halves of that bone being 
united by ligament below, and forming separate styles or “ clavicles.” 
The humerus of the Goura closely repeats most of the characters described in that of 
the Dodo: but its length is proportionally greater, being 3 inches 9 lines, nearly equal to 
that of the sternum or pelvis, whereas the humerus of the Dodo is little more than half 
the length of either sternum or pelvis. The processes for the attachment of the muscles 
are, nevertheless, fully as strongly developed in Didus (Pl. XX. figs. 12 & 14) as in the 
volant Doves (Pl. XXIV. figs. 8 & 9, Gowra); that, indeed, which is a ridge (7) on the 
back part of the shaft in Didus, is a mere rough surface in Goura, and does not show 
in Didunculus. The pneumatic fossa, which varies in depth in the two humeri of the 
Dodo, is in both relatively larger and shallower than in Gowra. ‘The pectoral process 
is thinner, but relatively rather more produced, in Didunculus. The humerus in @di- 
cnemus, Otis, and Charadrius has a more longitudinally extended, thinner, and more 
produced pectoral ridge than in Didus and the Columbidw; there is a more marked 
ectocondyloid tuberosity, which in Charadrius becomes a pointed process. 
There is nothing to be gained by giving the details of the more striking differences 
' Trans, Zool. Soc. vol. iv. pl. 24. fig. 4. 
