146 UR. W. K. PARKER ON THE STRUCTURE AND 



The small, oval, directly posterior occipital condyles are separated by a concave 

 space more than the width of both together, and more than half of this basal inter- 

 condylar tract is cartilaginous. 



Also a wide " cross " of cartilage intervenes between the four main liind-skull ossifica- 

 tions, below ; above, the superoccipital synchondrosis is narrow, and the prootic and 

 8x-occipital (fig. 1, pr.o., e.o.) of the same side are entirely confluent, the bony substance 

 reaches to the squamosal (sq.) under which the " tegminal edge " is soft. Even below, the 

 trigeminal nerve (fig. 2, V.) passes through the bone, which is not far from the girdle- 

 bone, over the optic nerve (II.). Some cartilage and three small membranous fontanelles 

 lie across the hind skull, behind the large heart-shaped principal space. The breadth 

 of the skull at the top lessens along the girdle-bone, in which, however, it spreads 

 out again gently in front. Tliis bone (eth.) takes v;p three-fifths of the orbital region, 

 it passes, in front, nearly to the boundary of its own (ethmoidal) region, and above, 

 runs a little along the septum nasi {s.v.). Over its wings this common ethmoid has 

 a small superorbital " eave " of cartilage. 



The nasal region is very large both ways ; it ends abruptly in front, has large cres- 

 centic roofs (fig. 1), a long and moderately deep septum (s.n.), and a wide floor (fig. 2). 

 The pro-rhinals (fig. 2, p.rh.) are slender, but well formed and uncinate. The super- 

 added cartilaginous valves of the external nostrils {ii.l^.u.l-., e.7i.) are large, and those 

 passages are wide apart. 



Very wide apart indeed are the internal nosti'ils (?.n.) ; they are large oval holes con- 

 verging forwards. The palato-suspensorial arch is large and well developed ; all its 

 parts are wide, for width characterises the whole skull and all its parts. Yet, in 

 essentials, both the cartilage and its grafted bones {pa.,pg.), with the condyles of the 

 quadrate and the pedicle {q.c, pd.), are quite normal. 



The Eustachian openings (eu.) are less than the inner nostrils, but are large; they are 

 oval, with the long axis directed outwards and a little forwards. The annulus {ci.ti/.) 

 is large, broad, and jierfect ; the stapes (fig. 4, st.) is large, oval, and flattish : it is 

 broader in front than behind. The iuter-stajsedial (i.st.) is a thickish subquadrate 

 segment, nearly half the size of the stapes ; the medio-stapedial is long, straight, and 

 its imperfectly ossified, wide, proximal end is scooped out ; the extra-stapedial (e.st.) is 

 a reversed spatula — it is narrower distally than proximally, and has only a fibrous 

 supra-stapedial band. 



The narrow stylo-hyal (fig. 2, st.h.) is confluent above; it increases only gently in size 

 downwards (fig. 3, chy.), has no hypo-hyal lobe {li.hij.), and soon reaches tlie basal plate 

 as it turns backwards. That jilate {h.h.hr.) is short, wide in front, narrow behind, has 

 small fore-turned aiiterior, and long, slender, posterior lobes ; the thyro-hyals (t.hy.) are 

 long and slender ; they diverge so as to be at a right angle with each other. 



The mandibles (fig. 3) are quite normal, but are long and slender; the dentary (d.) 

 is half the length of the ramus. 



The investing bones are normal but partake of the general flatness and breadth of 



