90 Prof. R. Owen on the Solitaire. 
removed; and then the homologue of the “os en ceinture”’ of 
batrachotomy and of the “ethmoid” 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 “ prefrontal ” 
is restricted by some who retain the term “ zthmoid”’ for the 
plates transmitting the olfactory nerves from the rhinencepha- 
lon. In Macropus and most other marsupials the corre- 
sponding extension is grooved longitudinally, as in Didus and 
Pezophaps; but the fissure transmitting to the nose the lacry- 
mal duct, anterior to the grooved lacrymal bone, in the bird, 
is reduced to a fossa with one or two foramina in the impla- 
cental mammal. 
The maxillary sends up a strong nasal process confluent 
with the outer branch(s') 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 nasals and nasal process of the premaxillary rise 
as a transverse bar (Pl. VIII. fig. 1, x), with a convex ante- 
rior border, above the rostral divisions of those bones ; in this 
character Pezophaps resembles Treron and Didunculus; while 
in Didus the premaxillary and nasal portions of the elevated 
basal tract are indicated by grooves therein. In both genera, 
as in recent doves, 1 and 22! are confluent with 1. Beyond 
the confluence the divisions of the nasal pair are separated by 
the nasal process of the premaxillary (22'). The imner divi- 
sion or normal part of the nasal is 1 inch 8 lines in length ; 
it extends forward for half that length along the outside of 
the premaxillary, then inclines mesiad beneath that bone, 
coming into contact with its fellow for six lines extent of their 
terminal pointed end; they underprop the nasal process of 
the premaxillary ; and thus we have, in the extreme variation 
of an extreme segment of the vertebral axis, the heemal spine 
closing the tubular series by overlapping the neural spine of 
its own segment. The under surface of the nasal process of 
the premaxillary is impressed by the shallow channel re- 
ceiving the underpropping fore part of the midnasals. 
The basi-presphenoid (Pl. VIII. fig. 2, 5,9) is 2 inches 
long in the male; it has no pterapophyses. 
* See, e. y., the prefrontals of Xiphias in my ‘ Archetype of the Ver- 
tebrate Skeleton,’ pl. i. fig. 5, 14. 
