5302 PROF. W. K. PARKER ON AGITHOGNATHOUS BIRDS, 
The bone itself (fig. 4, v) is concave above; it was formed from two symmetrical 
scythe-shaped moieties, each of which began as endostoses in the corresponding “ vome- 
rine cartilage :” they ossified it thoroughly, and then seized upon each alinasal wall, 
where they ended by turning inwards. But the broad cartilaginous band below (see 
fig. 4, 7. a. 1) has a separate bony graft, the ‘septo-maxillary” (fig. 6, s.ma); and this, 
with the extended bony matter in the nasal cartilages, gives the peculiar appearance 
the vomer of the adult bird has when viewed from below (fig. 6): it resembles the face 
of a bull, the ascending lamine being little ears, and the outturned septo-maxillaries 
its short diverging horns. The septum nasi ossifies in the adult :—in front, from ‘the 
ossification of part of the ale; and the freed trabecular part (#7) by its own centre, 
The compound “ yomer” of the adult Crow has therefore been formed from :— 
a. A pair of vomerine cartilages. 
b. A pair of vomerine centres (endostoses of those cartilages). 
c. A pair of septo-maxillaries—exostoses formed upon the following, namely 
d. The end of each inturned alinasal wall, combined with the end also of its 
“outgrowth ” the “ alinasal turbinal.” 
Then, as if this amount of metamorphosis were insufficient, the crura of the vomer 
coalesce with the ethmoid processes of the palatines (¢.pa), so that in each movement 
of the face the whole nasal labyrinth is carried forwards and backwards by the mobile 
pterygo-palatine arch. This second preoral arch has a short and stout suspensory seg- 
ment, the “ pterygoid ” (pg), which, however, as the bird grows older, becomes slenderer, 
especially behind, where it acquires the epipterygoid hook or “hamular process.” It 
flattens out horizontally in front, and then sends a spur to overlap the palatine. This 
becomes the “ mesopterygoid””—separate in a young flyer (fig. 5, ms.pq), but soon to 
ankylose with the palatine. 
The distal segment of this arch, the palatine (pa) is greatly longer than the pterygoid: 
with the fore end of the latter it tends to form a commissure, which is only completed 
by membrane; it is then bowed out on each side, and each moiety runs far forwards as 
a finely pointed style (fig. 1). Where it is overlapped by the pterygoid, there it is split 
mesiad into two lamine; these end in front in sharp spurs, to the upper of which the 
vomerine legs are articulated ; the lower or “ interpalatine processes” are merely united 
by a ligament to the maxillo-palatine spatule. 
If this were all, the palatines of the Crow would correspond with those of the Hemi- 
pod. But the first bony shaft does not calcify all the arch-moiety; it leaves an external 
outgrowth, which has time to become solid hyaline cartilage: this is the ‘ transpala- 
element (¢.pa), and it is a sure sign and correlate of complete wegithognathism. 
This free auricle of cartilage becomes, in a young summer-bird, a distinct bone (fig. 5, 
t,pa), ossifying at first by endostosis; and then, in the adult, it shows no sign of having 
ever been separate from the body of the palatine (fig. 6, ¢.pa, t.pa). 
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