796 
ME. W. K. PARKER OK THE STRUCTURE AND 
has reached the foremost orbito-sphenoidal patch (o.s. 1) ; towards the base it is growing 
towards the fore part of the basisphenoid ( b.s .). All the rest of the cranio-facial axis is 
still soft ; and we now see the large size of the separating cleft, through which the upper 
and lower turbinals (u.tb. and i.tb.) are seen. The grooves for the nasal nerve (n.n.) 
almost cut off the gnawed postero-inferior angle of the septum nasi ( s.n .) ; over the lower 
part of each groove there is a ridge of cartilage, from which in many birds there is an 
outgrowth partially occluding the nostrils, and strongly cemented to the lateral splints. 
The prenasal cartilage (p.n.) still lingers in front of the rounded fore end of the 
septum ; after this it rapidly disappears ; indeed it seldom lasts so long, this specimen 
being exceptional. 
The splint-bones are beginning to coalesce with the endoskeletal tracts ; the parietals 
(p>) and the squamosals (sq.) are partly fixed: the latter show a considerable surface on 
the inner side (Plate LXXXYI. fig. 14). All the rest of the splint-bones can be macerated 
away ; their relations are shown from above in fig. 15, where the nasals ( n .) are seen to 
have a considerable frontal portion. 
The vomer (fig. 14, v.) is attached to the maxillo-palatine plate (m.w.), being widely 
dislocated from the base of the cranio-facial axis. 
In the mandible the dentary (fig. 14, d.) and the splenial (sp.) are still separable from 
the fast-shrinking Meckelian rod (m.Jt.) ; but the angular (a.) and the surangular (su.) are 
partly anchylosed to the articular (ar.) ; this part, the counterpart of the bulk of the 
malleus, is now nearly ossified. 
A more advanced skull is shown in Plate LXXXY. figs. 10 & 11, and Plate LXXXYII. 
fig. 1 : here the free edge of the exoccipital wing ( e.o .) and that of the postfrontal ( p.f ‘.) 
are still unossified ; but the latter is now one with the alisphenoid, which is still separable 
from the basisphenoid ( a.s ., p.f., b.s.). 
A narrow suture now separates the perpendicular ethmoid from the basisphenoid 
(Plate LXXXVII. fig. 1 , p.e., b.s.) ; they now meet below the still unossified part of the 
presphenoid ( p.s .), which has, at last, appeared as a curved bony plate articulated by 
suture with the middle bar of the perpendicular ethmoid. Essentially a distinct bony 
patch, yet the presphenoid did not appear until the posterior orbito-sphenoid (o.s. 2) had 
affected its perichondrium ; this process differs nothing from the grafting of the rostrum 
on the cartilage below. The alisphenoids are seen (Plate LXXXV. fig. 11) to be almost 
completely transverse in their position ; but they overhang the postorbital space, being 
a continuation of the roof formed antero-superiorly by the orbital plates of the frontals 
(Plate LXXXYII. fig. 1, /.). The alisphenoidal fenestra (Plate LXXXY. fig. 11, a.s.f.) 
are nearly filled-in by periosteal layers. 
The squamosal is quite Batrachian in the Struthionidse ; it now suddenly foreshadows 
its counterpart in the highest Class. 
I have already shown its large inner face (Plate LXXXYI. fig. 14, sq.) ; but its outer 
face is enormously expanded (compare Plate LXXXYII. fig. 1 with those in my former 
paper, Plates is.-xiv.). The zygomatic process, in front of the articular facet, has not 
