DEVELOPMENT OF THE SKULL IN THE PIG, 



307 



al.s.) are cut through obliquely, so as to show only the j^oor part of the latter ; and the 

 cartilage beneath the pituitary body is made to appear thicker than it is in reality (see 

 Plate XXXIII. figs. 2 & 3, 2>y-)- On each side of the pituitary body the internal 

 carotids are seen passing to the " circle of Willis," and outside these the Gasserian 

 ganglia. Overlapping the whole are the orbito-sphenoids (o..v.) ; and on each side of 

 the flaps of the soft palate [s.pa.) Meckel's cartilages are severed ; and lower down the 

 ceratohyals [cJnj.), thyrohyals {t.hy.), and larynx {Ix.) are shown. 



The nineteenth section (Plate XXXII. fig. 5) is drawn a little more than half across, 

 and on a larger scale. The curve of the cranio-facial axis makes this and the succeeding 

 section very oblique ; and in this figure the basilar artery {h.a.) is tilted to show the 

 bulbous end of the notochord {nc.) : this thickish section is viewed from behind. The 

 notochord ends now in the region of the future " spheno-occipital synchondrosis ;" this 

 narrow part of the basilar plate or investing mass is subcarinate. The razor 

 has passed through the cochlea {cl.) parallel to the plane of its coils ; over this part of 

 the auditory sac, which is scooped above at the side, lies the great Gasserian ganglion 

 (5) ; and inside and above this the fore edge of the large superoccipital lamina [s.o.) is 

 seen, severed close to the edge, so that there is here a discontinuity between it and the 

 ear-sac, the reason of which is shown in the inner lateral view (Plate XXXIII. fig. 3, 

 au.^ S.O.), where a large rounded notch is seen in front of the occipital cartilage, bulged 

 out at this part by the lateral sinus. At some little distance from the cochlea the first 

 postoral (now a veritable " malleus ") is severed through its head, neck, and shoulders ; 

 the head is now flattened : this section shows the thin edge of this manubrium, the 

 thicker part being cut through in the next section (fig. 6, mh.). This view (fig. 5, m.t.) 

 well shows the imbedding of the manubrium in the membrana tympani, and the inner 

 and outer regions of the first postoral cleft, thus divided by the head of the bar. 



The twentieth section (Plate XXXII. fig. 6) is a little oblique from side to side; it is 

 thus practically double ;^ the left hand shows parts in front of those displayed on the right. 

 Here, on the left, the manubrium mallei [mh.) is cut through at its thickest, posterior part, 

 and its solid shoulder [ml.) is seen, the part which articulates with the incus. The incus 

 (?'.) is seen on the right side, hiding the manubrium partly, and having its " short crus " 

 cut away : the figure shows the hack of the thickish section. On the right side the section 

 is behind the notch on the base of the fore edge of the superoccipital {s.o.). Below and 

 outside the tympanic cavity {t.c.) the stylohyal [st.h.) is seen in oblique section as it 

 passes downwards and forwards, and mesiad of this there is the large jugular vein {j.v.) 

 with a coiled radicle. The notochord [nc.) is very clearly seen in the substance of the 

 basioccipital cartilage. On the right side the stapedial bud is seen projecting from the 

 auditory capsule just above the section of the promontory {st., pr.), and to this the orbi- 

 cular " capitulum " of the second postoral is applying itself limpet-like. The tive)/tf/- 

 first section (fig. 7) is from behind the left side of the last (reversed), and shows on the 

 whole what is displayed on the right ; in both (figs. 6 & 7) we see the opening of the 

 "aqueduct of the vestibule," and in this the "aqueduct of Fallopius " containing the 



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