DEVELOPMENT OE THE SKULL IN THE OSTRICH TEIBE. 157 



have here of that exquisitely perforate and highly complex mass which in the Mammal 

 receives the name of cribriform plate and upper turbinal. Close on its outside, and 

 tow^ards the top, the nasal branch of the ophthalmic nerve (Plate XIV. fig. 7, n.n.) is 

 seen creeping downvs^ards to supply the rich outgrowths of the wings of the nasal 

 septum. Below, the ethmoidal ala passes down into the pars plana (Plate X. fig. 17, 

 & Plate XIV. fig. 7, pp.) behind, and into the nasal wall, which grows down from the 

 root of the inferior turbinal. The pars plana is a high triangle, its base below, and it 

 is somewhat convex ; its free margin lies close to the perpendicular ethmoid, and on 

 its inner face is the middle turbinal. This outgrowth (Plate X. fig. 17, & Plate XIV. 

 figs. 9-11, m.t.h.) is a somewhat hourglass-shaped tent, with a small opening in front; 

 it is gently convex above, then slightly concave, and then thickens into two converging 

 roots below ; it is 3 lines long by 1 in breadth. The position of this tent is oblique, 

 for it passes downwards and forwards ; a valley of the same breadth as this turbinal 

 separates it from the infolded upper turbinal; below this true olfactory region lies 

 the hinder part of the inferior turbinal (Plate X. fig. 17, i.t.h.., a.i.t.), the last folds of 

 which can be seen in the middle nares, when the skull is looked at from below. Both 

 the upper and lower turbinals lie in the orbit (Plate XIV. fig. 1), which is bounded 

 in front by the descending portion of the large lacrymal {I.) ; inside this bone, and 

 further forwards, inside the ascending plate of the prevomer (Plate XIV. fig. \,p.v.), 

 we have the inferior turbinal, which has its largest volume below the broadest part of 

 the nasals, where the ossification of the upper ethmoid at present ends. A section at 

 this part (Plate X. fig. 19) shows a very unexpected richness of cartilaginous out- 

 growth, such as is seen in no other known bird, the Emu making the nearest approach 

 to it. The septum nasi [s.n.) is rather thick at this part, very swollen below, where the 

 trabeculse lay, and somewhat thickened also in the middle ; above it gives ofi" its alse 

 (al.s.), which rise in a rounded manner, and then curve downwards and outwards. At 

 a line from the mid line the alar lamella splits, the outer plate being moderately convex 

 in section, and forming the cartilaginous nasal wall, whilst the inner plate curves 

 abruptly inwards, forms nearly a semicircle, and then begins to give off secondary and 

 tertiary lamellee (i.t.b.). There are twenty of these folds on each side, nearly a third 

 more than in the Emu, but formed after the same fashion, some of them being single 

 (secondary), and some double and even treble (tertiary lamellae). The outer nasal wall 

 passes below the inferior turbinal folds, and ends behind in a curious thick blunt hook 

 (Plate X. figs. 18 & 19, & Plate XIV. figs. 1 & 7, a.i.t.), on the convexity of which 

 the base of the antorbital plate of the lacrymal rests, and which ends externally inside 

 the zygomatic process of the prevomer (p.v.). Both behind and in front (Plate X. 

 fig. 18) the turbinal folds become simpler ; but they reach nearly to the anterior nasal 

 passage in front, and form a roof to the middle nares behind. There is therefore no 

 special turbinal to the alinasal cartilage, as there is no actual boundary line between 

 these two regions. This makes the alse nasi look larger than they are (Plate XIV. 

 fig. 1, al.n.) actually, and this is one of those most interesting instances of the very 



