76 
IOWA ACADEMY OF SCIENCES. 
THE MORPHOLOGY AND FUNCTION OF THE 
AMPHIBIAN EAR. 
BY H. W. NORRIS. 
In the struggle for existence as individuals the Amphib- 
ians, or Batrachians, seem to have a minor position. For 
the most part of insignificant size, with poorly protected 
bodies, and with retiring and inoffensive habits, these 
forms which we know as toads, frogs and salamanders,, 
seem to be poorly adapted to maintain their species. 
From what the paleontologist tells us, we may well believe 
that the Amphibians as a class arose, flourished, and then 
declined to their present insignificant proportions long 
ago. It is because of the relationships of this group that 
it is of profound interest to science. It forms a connecting 
link, or rather a series of connecting links between the 
strictly aquatic Vertebrates, the Fishes, and the terrestrial 
forms. Presenting two distinct phases, a larval aquatic 
and an adult terrestrial condition, it presents for our 
observation the actual evolution of an aquatic, branchiate 
form into a terrestrial pulmonate form. Furthermore 
some forms retain the branchial organs throughout life, 
while others hardly give us a hint of a much shortened 
aquatic stage. This metamorphosis is not merely super- 
ficial, but is accompanied by profound morphological and 
functional changes. 
Experiments carried on in recent years, notably by Pro- 
fessor F. S. Lee, have made it very probable that the ear 
in Fishes is not an organ of hearing, but rather an organ 
of equilibration. That it has this latter function in 
all Vertebrates is very well known. It is then in the 
Amphibia that the ear changes from an organ of equili- 
bration alone to an organ of hearing, for it is certainly 
