4) 
tional depressions from the rugose, somewhat overhanging hind tract of the parietal 
region (ib. 7), ‘The temporal fossa is larger, relatively and absolutely, in Pezophaps 
than in Didus; it resembles that of Zreron. ‘The elevation of the frontal region is 
due, in Pezophaps, as in Didus and Treron, to excess of bony cellular diploé, and takes 
place in advance of the orbits in all Columbidw. The interorbital tract of the cranium 
(Pl. V. fig. 1, 1) rises from the premaxillo-nasal platform (ib. 15, 22’) more abruptly 
in Pezophaps than in Didus; but it sooner subsides, and the fronto-parietal tract, or 
vertex, is flatter. This tract is smooth, but surrounded by a broad rugose elevated 
border, continued from the superorbital ridge backward over the temporal fossa, then 
across the postparietal region (ib. 7) to meet the ridge on the opposite side. ‘The 
superorbital tracts converge forward to form the frontal convexity. This, however, is 
mesially cleft, exposing a deeper-seated smooth tract, over which a bony fringe projects 
on each side. This structure exists ina minor degree in the female; the superorbital 
tract is more rugose in the male than in the female Pezophaps. 
The chief difference between Didus and Pezophaps in cranial structure is the degree 
in which the cancellous tissue is developed between the outer and inner “ tables,” the 
minor quantity of that tissue in Pezophaps causing less elevation and convexity of the 
frontals above the orbits as compared with that part of the cranium in Didus, 
‘The lacrymal, coalesced with the prefrontal part of the frontal, curves down and back 
in front of the orbit; it is impressed by a deep, wide, smooth, longitudinal channel 
externally, conducting the duct to the naso-lacrymal orifice anterior to the orbit. 
To view the neurapophyses of the nasal vertebra, the nasals, premaxillary, and 
coalesced part of the frontals must be removed; and then the homologue of the “os en 
ceinture ” of batrachotomy and of the ‘thmoid” of anthropotomy is brought into view, 
with part of the confluent olfactory capsules, 
The essential elements of the anterior terminal segment have undergone extreme 
modification, and travelled far from the almost typical condition which they present in 
most fishes }. 
In the bird strong processes answering to diapophyses are extended outwards from 
the neurapophysial or essential parts of the prefrontals; and to these the name “ pre- 
frontal” is restricted by some who retain the term “ wthmoid” for the plates trans- 
mitting the olfactory nerves from the rhinencephalon. In A/acropus and most other 
marsupials the corresponding extension is grooved longitudinally, as in Didus and 
Pezophaps; but the fissure transmitting to the nose the lacrymal duct, anterior to the 
grooved lacrymal bone, in the bird, is reduced to a fossa with one or two foramina in 
the implacental mammal. 
The maxillary sends up a strong nasal process confluent with the outer branch (19’) 
of that bone, which articulates with the swollen fore part of the frontal, outside the 
base of the inner division (15) of the nasal bone. The common coalesced bases of the 
' See, ¢. y., the prefrontals of Xipdis in my * Archetype of the Vertebrate Skeleton,’ pl. i, fig. 5, 14, 
