320 MR. W. K. PARKER ON THE’ STRUCTURE AND 
In the Pig the bullar ossifications are found in a very soft stroma of connective tissue, 
and not in thin cartilage; yet that stroma is connected with the outer and lower edge of 
the opisthotic and prootic regions; it is the membranous floor of this huge air-cell. 
The “os bullie” already developed is seen in section, in its fore part (fig. 11, 0.6.), a 
little in front of the auditory capsule, at the edge of the lower limb of the tympanic 
(ty.). The parts of the facial system of cartilages entering into the structure of the 
middle ear are shown in figs. 1 & 12; the “*manubrium mallei” (fig. 1, md.) is now 
ossified, and so also is the incus (figs. 12, 7.). The lingual part of the hyoid arch is con- 
tinued upwards to the epiotic region (figs. 1 & 5, st.4.), and behind this flattened rod 
the portio dura nerve is seen escaping. 
The little ceratohyal (e.y.) twms backward to articulate with the basal piece, to 
which also is attached the thyrohyals (fig. 1, 0.4., t.hy.); the latter three parts belong 
to the “ third postoral arch.” 
The ossification of the lower jaw (fig. 1, d.) is almost complete, the unossified cartilage 
being principally condylar. 
A series of sections selected from a large number now remain to be described; they 
will more fully illustrate this stage. 
The first of these (Plate XX XV. fig. 6) is through the anterior third of the “ inferior 
turbinal ;” the pedate lower edge of the ‘ aliseptal” cartilage here is seen to be coiled 
inwards above and below, the common back of the two coils lying towards the septum 
(7.¢., s.v.). The sudden inbend of the aliseptal lamina higher up is the rudimentary 
“nasal turbinal”’ (7.¢b.); below the septum is the vomer (v.), and below this the palatine 
processes of the premaxillaries are seen ( p.p..). The nasals (x.), the side of the pre- 
maxillaries, and maxillaries ( pa., a.) show very thick in the section. On each side of 
the vomer the “recurrent apices of the trabecular horns” are still present (7¢.c.). 
The second section (fig. 7) is through the complex upper and middle turbinal regions 
(w.th., m.tb.) and the high part of the perpendicular ethmoid (p.e.). The olfactory 
crura (1) are also cut through as they lie on the cribriform plate (e7.p.). This widest 
part of the true olfactory region is roofed in by very massive frontals (7); the thin 
lower edge of these bones is the orbital plate. The vomer (v.) is here very deep ; on 
each side of it the posterior nares are cut through, and these are protected by the 
long scoop-shaped processes of the palatines (pa.). A part of the maxillary is seen 
on each side of a large molar tooth with its pulp; and above, the outer piece of bone is 
the jugal (/.). 
The third section (fig. 8) is through the low part of the perpendicular ethmoid and 
the end of the cribriform plate, where it overlies the middle turbinal (i.¢b.) only. ‘The 
palatines (pa.) are here at their fullest development, their scooped portion underlying 
the end of the nasal wall (2.w.), and their subvertical plate sending inwards the palatal 
part of the hard palate. 
with the head of a new-born Hyrax; and in this I found a large bulla, ossified separately from the true tym- 
panic annulus,” and evidently formed in a shell of true cartilage. 
