282 PROF. OWEN ON THE ANATOMY 
in three principal convolutions, and its connexions were as usual in birds. It com- 
mences with a thin slit-like mouth, with entire margins, two inches in width, but soon 
contracts to a diameter of ten lines ; it thence proceeds to expand very gradually to the 
width of an inch, and is thus continued to the uterine or terminal segment: this portion 
is two inches and a half in length, and one inch and a half in diameter: its inner sur- 
face was studded with slightly arborescent calcifying follicles, arranged in transverse 
rows. The lining membrane of the principal part of the oviduct was thrown into longi- 
tudinal rug@; the tube communicated with the cloaca by a short, contracted, and ob- 
lique canal and orifice, with tumid margins. Both the upper and lower mesometries 
presented the usual radiated muscular structure. 
Osseous System. 
The skeleton (Pl. LIV.) of the Apteryz offers the same general form as the entire bird ; 
but while it exhibits the Struthious disproportion between the anterior and posterior 
extremities, it shows that all the ordinary bones of the wing exist, though in their 
feeblest state of development. 
With the exception of the parts of the skeleton concerned in the formation of the 
nasal and auditory cavities, none of the other bones of the Apteryzx are perforated for 
the admission of air, nor do they exhibit the pure white colour which characterizes the 
skeleton in other birds. In their tough and compact texture they resemble the bones 
of the Lizard tribe. 
The skull (Pl. LIIL.) of the Apteryz is chiefly remarkable for its smooth, expanded, 
elevated, pyriform cranial portion, the total absence of supra-orbital ridges, the com- 
pleteness and the thickness of the inter-orbital septum, the great development of the 
ethmoid, the small size of the lachrymal bones, and the expansion of the nasal cavity 
behind these bones: the combination of the depressed with the elongated and slender 
form of the beak is of course as well marked in the skull as in the entire head already 
described. 
The occipital region of the craniwm has a pretty regular semicircular contour, and dif- 
fers from that of other Struthious birds in the greater relative extent of its base, and in 
the comparatively slight lateral sinuosities due to the temporal depressions. The single 
hemispherical tubercle in the basi-occipital, for the articulation with the atlas, has not 
the vertical notch at the upper part observable in the Ostrich and Emeu, but is entire 
as in the Rhea; and the plane of the occipital foramen has the same aspect as in that 
bird, in which it is more nearly horizontal than in the Ostrich. The supra-occipital plate 
forms a somewhat angular projection, corresponding with the small cerebellum within, 
and is bounded on each side by a vertical vascular groove, terminated by a foramen above 
and below : external to these grooves the ex-occipitals extend outwards and downwards, 
in the form of obtuse processes, compressed in the antero-posterior direction, slightly 
en 
