526 PROF. W. K. PARKER ON AGITHOGNATHOUS BIRDS. 
as a key than the far-western Homorus ; for in Gymmorhina, ossification runs riot, and 
the very numerous osseous centres melt into each other, if not here, yet there; at some 
point or extremity, or jutting snag, they lose their individuality, making the morpho- 
logist wonder why this puzzle grew from so many pieces. ‘The notch in the basifacial 
axis is a very large triangle, with its apex upwards; it is perfect, and the point of the 
parasphenoid does not reach it. In front of the notch, or hingé, is the well-ossified nasal 
septum, which is fenestrate and deep in front, and shallow behind; and its lower edge 
and subnasal ale are ankylosed to the intensely ossified nasal floor (fig. 5, 7.7); and 
this is a continuation of the solid, bony alinasal. Where they arise, there the alinasal 
turbinals are ossified; for the rest, they are soft, save at the end, where the upper 
vomerine lobes (figs. 5 & 6, v) have run into them, by grafting (fig. 7, v, 7. a. 1). So also 
the aliseptal has coalesced by bony union with the outer facial walls, as in the mammal, 
and has also, as in the young mammal, a top-shaped bone, formed by ossificaticn of its 
posterior end, the part attached to the bony “ pars plana.’ Hence, in seeking in the 
adult for the “ trabecule cranii,’ we find that foremost facial arch metamorphosed into 
a great variety of substructural bars and beams and outgrowths of periosteal bone. 
The apices of the two early coalesced bars are involved in the great ‘“‘ temporal wings of 
the parasphenoid,” forming the ‘“ anterior tympanic recess” (fig. 5, a. ¢.7); then the 
narrowing portion forms the sides of the sella turcica ; narrowing still, it forms the base 
of the interorbital fenestra, where the two primordial bars first formed their commis- 
sural union. 
A continuation of this part substructs the septum between the functional part of the 
nasal sacs—the perpendicular ethmoid; there the notch severs the once double bar, 
and the rest of the trabecule form the base of the partition between the vestibular 
parts of the nose and also, where the trabeculw keep flat, the floor of the nose between 
the outer nostrils. The azygous process of the trabecule (the prenasal cartilage) is 
absorbed, being aborted by the huge splints formed upon it, as upon a model: I refer 
to the foremost facial splints, the praeemaxillaries. Yet this does not exhaust even the 
“ endo-skeletal” parts of this arch; for the lateral ethmoid has a small os uncinatum 
(fig. 8, p. p, 0. uw) attached to its lower angle; this is the conjugational bone between 
the two preoral arches. 
I have spoken of the dense and everywhere ankylosed premaxillaries ; these are the 
foremost splints: but five more secondary ossifications belong to the trabecular arch ; 
these form a single bone in the adults. But these five osseous elements were brought 
into relation with a pair of “ vomerine cartilages.” All these things are hidden in the 
curious three-horned vomer of the adult ; and this now single bone has lost its freedom, 
being bound to the ascending plates of the palatines behind, and grafted upon the ali- 
nasal turbinals in front (tig. 5, v, e.pa; figs. 6 & 7, v, 7. a. 1); also it is articulated strongly 
.by a kind of zygapophysis to the maxillo-palatine on each side (figs. 5, 6, 7, v, map). 
The stones and the cement used in this building, the strength and safety of which have 
