THE SENSE CAPSULES. 27 
and outer chamber. [rom the outer 
chamber the Eustachian canal passes. 
Its connection with the ear, it should 
be remembered, is quite a secondary 
-one, it forming no essential portion of 
the auditory organ. It arises as a 
modification of the embryonic hyo- 
mandibular cleft, persisting in certain 
fishes as a spiracle. 
iii. The auditory ossicles. Morphologic- 
ally, the chain of three small bones 
lying across the tympanic cavity from 
‘the tympanic membrane to the mem- 
brane across the fenestra ovalis, should 
be treated of together with the bones 
of the mandibular and_ hyoidean 
arches. Their very close relationship, 
however, to the auditory organ makes 
it more convenient that they should 
be examined here. 
a. The malleus is a small stout bone, 
consisting of a body and two processes. 
The larger process, the manubrium, 
is very distinct, being long, thin, and 
strongly curved, and attached to the 
tympanic membrane. The smaller 
process articulates with the tympanic 
bone in a small fossa. 
8. The ineus articulates with the malleus, 
this portion being produced and form- 
