664 GEOLOGICAL SVRVEY OF THE TERRITORIES. 
b. s., the basi-sphenoid, the centrum of the vertebra. The hzmal arch 
we see in the “hyoid,” which here shares the same fate of its neighbor 
in the occipital vertebra, insomuch as it is ununited’to the superior arch 
by either osseous connection or by articulation, for in all living birds 
the hyoid, the well-known bony support of the tongue, depends en- 
tirely upon its muscular and ligamentous connections to retain its rela- 
tions with the cranium. The manner in which the disjoined neural spine 
of the parietal vertebra goes to form the posterior fontanelle in the half- 
grown bird has already been sufficiently dwelt upon. The bone P, as 
detached in an individual of this age, is quadrilateral in outline, ex- 
cessively spongy and light, owing to the paucity of compact substance 
over quite a large share of diploic tissue, which is chiefly deposited in 
a protuberance on its inner table, which protuberance, in union with: 
the fellow of the opposite side of the complete cranial vault, forms two 
concave surfaces out of the remainder of the superticies, essential por- 
tions of the ep- and prosencephalic fosse. 
Superficially, these elements are smooth and convex, and in the adult, 
after consolidation, exhibit some faint evidence of a parietal eminence 
on either side—more marked elevations, however, occurring in the spine 
of the vertebra beyond, immediately anterior to the suture termed in 
Anthropotomy the “coronal.” With the exceptions of the tympano- 
mastoidal articulation and the connections between the mastoids and 
petrosals, the majority of the articulations of this vertebra in the mid- 
aged bird may be classed among the variety known and described in 
works upon human anatomy as the ‘‘squamosal”—the parietals being 
beveled above to accommodate themselves to the frontals. 
The alisphenoids are separated from each other mesially by nearly 
half a centimeter; above they meet the frontals, below the basi-sphe- 
noid, and laterally the mastoids—the lower and outer angles almost 
reaching the cup-shaped articulation for the tympanics. This segment 
seems to ossify from its borders towards the center, leaving a foramen 
that is eventually closed in. Touching this point, Professor Parker 
says, when treating of the development of the skull of the Common 
Fowl, ‘‘ From the hinder half of the basisphenoidal region a considerable 
elongated alisphenoidal lamina arises (a. s. Fig. 59), passing outwards 
and backwards on either side in the cranial floor, and ascending a little 
into the side wall; coalescing at its extremity with the periotic mass, but 
leaving an elongated space unfilled by cartilage between the two tracts. 
The cranial surface of the alisphenoid conforms closely with the concave 
curvature of the hinder part of the cranium (see Fig. 62).” (Morphol- 
ogy of the Skull, Lond. 1877, p. 230). And further on, ‘‘A membra- 
nous fontanelle (a. s. f.) arises in its center; and both in front and be- 
hind this distinct ossific centers appear in the cartilage; these after- 
wards unite to form one alisphenoid bone.” (Ibid p. 236). 
Professor Huxley, in treating of the development of the cranium, says 
of this bone— 
_ “Yn front of the auditory capsules and of the exit of the third divis- 
ion of the fifth nerve, a center of ossification may appear on each side 
and give rise to the alisphenoid, which normally becomes united below 
‘with the basisphenoid.” (The Anat. of Vert. Animals, p. 24.) 
This bone, on its mid and lower border, presents for examination the 
half of the “foramen ovale,” which is completed by meeting the centrum 
of the vertebra. It is for the transmission of the trigeminal nerve into 
the orbital cavity. Laterally there is developed a-quadrate apophysis 
(the parapophysis of the vertebra?), which joins with a similar, subse- 
quently scale-like process coming from the mastoid, resulting in a fora- 
