DEVELOPMENT OE THE SKULL OE THE COMMON FOWL. 
799 
against which the aliseptal fold terminates as a free lamina, closely tied by fibrous tissue 
to the nerve-bridge. Besides the proper nasal floor, we have here a true bony palatine 
floor ; for here the palatine plates of the maxillaries (mx.,f.mx) are at their fullest deve- 
lopment, and are expanded where they nearly meet each other and have the vomer (v.) 
wedged in between them below. A section through this part of the skull in the Turtle 
(< Chelone ), in the Pangolin ( Manis ), or in the Cat (Felis) would show precisely the same 
disposition of these parts, the vomer wedging itself in between the palatine plates of the 
maxillaries, which fail, where the vomer crops out, to meet each other at the mid line. 
At this part the upper and lower crura of the nasal ( n .) are cut through ; the dentary 
part of the premaxillary ( d.px .) is becoming thin, the maxillary is at its greatest breadth, 
and the palatine is growing thicker. The feeble, ichthyic maxillaries (m.x.), instead of 
protecting the side of the face, are seen to be almost entirely at its base. 
The next section (fig. 4) is taken where the large chink is seen in the upper view 
(fig. 11, between al.e. and al.n.) ; here the aliseptal fold ends exactly where it has given 
off the inturned inferior turbinal coil (i.tb.) ; this coil has exactly two turns. Below, the 
posterior edge of the nasal wall ( n.w .) is seen curving a little upwards where it touches the 
nasal nerve ( n.n .). This section also passes through the maxillo-vomerine floor (p.mx., v.) ; 
and here the nasal processes of the premaxillaries (n.jpx.) are flat, and the dentary pro- 
cesses (d.jpx.) are very small ; the saw has passed through the nasals (n.) close in front 
of their bifurcation. 
The next section (fig. 5) cuts through the nasals behind their bifurcation, and just 
takes off the fore end of the jugal (j.) ; two portions of the maxillary (mx.) appear in 
this section — namely, the zygomatic process, and the posterior edge of the palatine plate. 
As this section is taken behind the lateral chink, the nasal wall (n.w.) reappears below 
the inturned inferior turbinal outgrowth (i.tb.). The nasal nerves (n.n.) are seen 
turning downwards, and by their close contiguity they have aborted the septum nasi at 
this part; in many Birds, especially the Baptores, the postero-inferior angle of the 
septum is almost sawn off by these nerves. Another branch is seen to perforate the 
winged top of the septum, close below the nasal processes of the premaxillaries 
(n.jpx.). 
In the next section (fig. 6) a front view is given of the end of the inferior turbinal 
(i.tb.), and of the anterior face of the upper turbinal (u.tb.) ; this section passes through 
the cranio-facial isthmus, which is still surmounted by the flat ends of the nasal processes 
of the premaxillaries (n.jpx.). On each side, the nasals (n.) form the roof-bones, which 
are flanked by the lacrymals (l.). The upper turbinal (u.tb.), like the lower, is seen 
to be an involution or outgrowth of the nasal wall (n.w.) ; and here at this point they lie 
one above the other ; this is also shown in the lateral view in fig. 10. 
In the next section (fig. 7) the inferior turbinal is cut away, and the interior of the 
upper turbinal (u.tb.) is exposed. Although appearing as a distinct outgrowth ante- 
riorly (fig. 6, u.tb.), the upper turbinal is a mere bagged condition of the aliethmoidal 
lamina (al.e.) further back (see figs. 7 & 10). 
