OF GALLINACEOUS BIRDS AND TINAMOUS. 215 
but, although partly ossified, the inferior turbinals of the Tinamou are not so complicately 
folded as in the Emu and the Cassowary. There is a rudiment of the fissure which, in 
typical birds, grows upwards and separates the septum from the vertical ethmoid to form 
the hinge; it is two linesslong, oval, with its longest axis from fore to aft; is divided 
behind by a thread of bone ; it allows the lower part of the turbinal folds to touch each 
other at the axis of the skull, and it is converted into a foramen by having the great basi- 
sphenoidal ‘‘ rostrum ” running beneath it. In many typical birds this rostrum ends as 
a free style beneath the cranio-facial fissure—that fissure which allows the formation of 
the hinge of the face on the skull. The remarkably strong separate septum of the Sand- 
grouse thus agrees with that of the Tinamou in the degree, but not in the source, of its 
ossification : it is ornithically separate ; whilst the cranio-facial axis of the Tinamou is 
arrested at an early stage, and is continuously ossified from the great ethmoidal plate as 
in the typical ‘‘ Struthionide.” 
The nasals of the typical bird do not end at the hinge, as might be supposed by a 
cursory observer of the adult skull; their broadest and thickest portion is behind the 
hinge, and they force the pointed anterior ends of the frontals to the side. Where they 
are more feebly developed posteriorly, as in the Fowls and still more in the Ostriches 
(Pl. XLII. fig. 2, n.eth.), the ethmoid is apt to appear, as in fishes, on the top of the head. 
Notwithstanding the separate condition of some of the lateral cranial elements in the 
skull of the Tinamou, the posterior part of the nasals, the anterior part of the frontals, 
and the upper part of the lachrymals all form one continuous bony mass (Pl. XL. 
figs. 2 & 3). The anterior part of each nasal, viz. the upper and lower crura, by their 
feebleness show the bone to be but small; and there is a touch of the Plover in the ap- 
pearance of the bony part of the ali-ethmoid between the crura of the nasals. In the 
Pigeon, Sandgrouse, and Hemipod this condition is still better developed, and in them 
the part of the prefrontal which is there exposed is thick and spongy, and not thin and 
papery as in the Tinamou and Plover. The upper crus of the nasal, which runs external 
to and below the nasal process of the premaxillary, does not reach the end of the nasal 
fossa ; it nearly reaches that point both in the Plover and the Rhea, but is much shorter 
in the Emu. The lower crus, which is absent in the Rhea (Pl. XLIL figs. 2 &4,n.), and 
a mere style in the Ostrich and Emu, does reach the lateral edge of the upper jaw in 
the Tinamou (Pl. XL. fig. 3): it articulates with the ascending process of the prevomer. 
It is a very feeble, rounded rod of bone above, is bowed outwards at first, and is there, 
as it were, squeezed under the anterior edge of the lachrymal. This process then 
slowly thickens, descends with a slight lean forwards, and becomes broader and some- 
what pedate where it articulates with the prevomerine spur below. In the dry skult, after 
the large alinasal and anterior part of the external wall of the inferior turbinal cartilage 
have been removed, the bony nasal fossa is very large indeed. It is more like that of the 
Plover (Pl. XXXVII. fig. 4, n.) than that of the Ocydromus, and very unlike that of the 
Fowl (Pl. XXXVI. fig. 9), and is quite in advance of the nasal fossa of the typical 
VOL. V.—PART III. 2F 
