Mr. Carlisle on the Physiology of the Stapes. 205 
ever, articulated to a cartilage, as in birds ; but to a small 
bone performing the office of the manubrium of the malleus. 
In birds, a slender bone passes to the fenestra vestibuli, 
from a cartilage fixed to the membrana tympani : it is called 
columella, having received that name from Julius Casserius. 
The capitulum of the columella in birds is slightly expanded, 
and is joined to an obtuse-angled triangular plate of cartilage, 
which I have called cartilago columellas, ( vide letter t, ) the 
longest side of the triangle is attached to the membrana 
tympani. In some species of birds a small foramen occurs in 
the middle of this plate, but in many others it is entire. 
A strong muscle is inserted into the shorter angle of the 
cartilage, which draws it downward, and thus elevates the 
opposite angle in the center of the membrana tympani, so as 
to render it conical externally. Two lateral ligaments steady 
the articulation of the cartilage with the head of the columella. 
The columellas in birds are less brittle than the ossicula 
auditus in the mammalia ; their bases are exactly fitted to the 
fenestra vestibuli ; and that part of those columellas nearest 
the base is generally of a reticulated texture. 
The amphibia are provided with columellas, in their form 
and adaptations resembling those of birds : the cartilage is 
here, however, united to the under surface of the true skin, 
without any apparent application of muscles to alter its tension. 
The substance of the columella is even less hard than in birds; 
and its basis is considerably smaller than the fenestra vesti- 
buli. The cavity of the tympanum has no lateral cells, and the 
Eustachian tube is short, and wide, seemingly for the purpose 
of receiving sounds conveyed through the medium of air. 
From the evidence of these facts, together with the com- 
