924 
MR. A. FRASER ON THE DEVELOPMENT OF THE 
Fig. 31. Transverse vertical section, showing malleus and its relation 
to sulcus tympanicus and meatus auditorius externus, tympanic 
annulus, basis cranii, and thyroid cartilage. 
Fig. 32. Transverse vertical section through a plane posterior to fig. 31, 
showing ganglion acusticum, and the cochlear and vestibular 
portions of the nerve, basis cranii, thyroid cartilage, tympanic 
annulus, periotic capsule, incus, stapes and arteria stapedio 
maxillaris, articulation between incus and stapes; and vestibule 
of labyrinth. 
Fig. 33. Longitudinal vertical section made parallel to middle line of 
head, showing malleus, incus, periotic process, hyoidean 
cartilage, facial nerve with its mandibular division, meatus 
auditorius externus, periotic capsule with the canals partly in 
dotted outline, recessus cerebelli for flocculus, and exoccipital 
cartilage. 
Fig. 34. Longitudinal vertical section from same series as fig. 33, in 
a plane more internal, showing mandibular cartilage, and 
membranous splint of bone immediately underneath it, tym¬ 
panic annulus, meatus auditorius externus, stapedius muscle 
in which there is no cartilage, facial nerve, periotic capsule and 
canals, and hyoidean cartilage. 
PLATE 58. 
Fig. 35. Longitudinal vertical section in a plane more internal than fig. 
34, showing meatus auditorius externus, sulcus tympanicus, 
manubrium and posterior process of the malleus, hyoidean 
cartilage, arteria stapedio-maxillaris, and stapes, facial nerve, 
periotic capsule, and exoccipital cartilage. 
Fig. 36. Nearly horizontal section above the level of tympanic sulcus, 
showing periotic capsule and process, ganglion and trunk of 
facial, incus and malleus with articulation between them, 
mandible, pterygoideus internus muscle, gasserian ganglion, 
and its maxillary and mandibular divisions. 
Fig. 37. Nearly horizontal section from same series as preceding figure 
but cutting tympanic sulcus, showing stapes and its relation 
to periotic capsule, and long crus of incus, facial nerve, stapedius 
muscle, neck of malleus, mandibular cartilage, tympanic 
annulus, tensor tympani muscle, and pterygoid cartilage. 
Fig. 38. Nearly horizontal section in a plane ventrad to that of fig. 37, 
showing meatus auditorius externus in part, sulcus tympanicus, 
