148 MR. W. K. PARKER ON THE STRUCTURE AND 



and just a little cartilage is left on the outside of the wings ; the bony matter reaches 

 half way between the foramen opticum and the foramen ovale (II., V.). 



The tract of uuossified skull-wall round the optic passage is only one-fourth the 

 extent of the mid skull, for the girdle-bone (eth.) is very large; in front, above, it 

 occupies half the nasal roof (fig. 5, al.n.), and below, it runs up to the dentigerous 

 lobes of the vomers {v.). 



Under the roof-bones (fig. 5, /p.) the three normal fontanelles can be seen, and as 

 those bones only reach, in front, halfway fi-om the foramen magnum to the transveree 

 end of the snout, the girdle-bone is but httle roofed in above. Below, the bone passes 

 into the ethmoidal wings, but above, there is a considerable selvedge unossified ; this 

 is the apiculate superorbital (s.ob.). 



The pre-cranial mass, which is the fore half of the ethmoidal, and all the nasal region, 

 is square, and its breadth is equal to the widest part of the roof in the orbital region. 

 Its fore edge is almost directly transverse, being only gently rounded. 



The depth of the nasal region is only moderate (fig. 7) ; the septum (fig. G, s.n.) is 

 very thick ; the floor and roof (figs. 5 and 6) are equal in width ; the pro-rhinals {p.rh.) 

 are small and wide apart outside the nerve outlets, which also are wide apart. 



The external nostrils (figs. 5 and 7, e.n.) are very wide apart, and the nasal roof 

 {(il.n.) is very thick over then^ ; so, also, the second upper labial [u.l~.) is a thick cres- 

 centic valve. The 1st upper labial {u.l^.) is rather large, and the nasal process of 

 the premaxillary {px.) is grafted upon it, ossifying much of its substance. The 

 internal nostrils (i.n.) are very wide apart. The palato-suspensorial arches are not 

 large in proportion to the skull proper ; and they have only the average ossification, 

 the two bones {j)a., j^O-) leaving a considerable tract unaflected. The palatines 

 (fig. G, pa.) are thin, straight, splint-like bones becoming twice as wide at their outer 

 end as at their inner. The curved and bifurcated pterygoids (pg.) are moderately 

 strong ; the inner fork on the pedicle is half as long as the outer, which runs inside 

 the quadrate (q.c). Both the pedicle and the quadi-ate are formed of a solid mass of 

 cartilage, especially the former [pd.), which forms, here, the most massive condyle I 

 am acquainted with, at this part. This sinuous facet glides on a definite tract of 

 basal cartilage, which is confluent, externally, with the stylo-hyal (st.h.). The quadrate, 

 above the reniform condyle {q.c), is not ossified to any noticeable extent. 



The Eustachian openings (eu.) are large, oval, and have their long axis directed 

 forwards. The annulus (fig. 7, a.ty.) is large, broad, and complete; its edge has a 

 strong rim. 



The mandible (fig. 7) is normal ; it is rather slender, and has a high coronoid process 

 to the articulare (ar.). 



The stapes (fig. 9, st.) is oval, and not raised externally to any appreciable extent. 

 The inter-stapedial (i.st.) is massive and semi-ossified ; it runs some distance on the shaft. 

 The medio-stapedial {7n.st.) is a rather slender, terete rod ; the extra-stapedial (e.st.) 

 is large and spatidate ; the {s.st.) supra-stapedial is cartilaginous and confluent, above. 



