IOWA ACADEMY OF SCIENCES. 
77 
true that many of the toads and frogs have very acute 
auditory powers. We are not able to show experimentally 
whether there are any Amphibians in which the -sense of 
hearing is wanting, since the bony skull and the small size 
of the ear capsule almost preclude the possibility of accu- 
rate experiments such as have been performed upon the 
Dog-fish. But we are justified, it seems to me, in basing 
some conclusions on the study of the structure of the 
Amphibian ear. 
In the general form and relationships of its parts the 
inner ear, or labyrinth, of Amphibia, is essentially fish- 
like. The only important new structures are the pars 
basilaris, and closely associated with it the perilymphatic 
canal, the two structures that combine in the higher 
classes of Vertebrates to form that complicated organ, the 
cochlea. In Proteus, Necturus, Siren, Amphiuma, and 
presumably in that blind branchiate form, Typhlomolge, 
from the subterranean streams in Texas, the pars basilaris 
is wanting. In all other Amphibia, as far as investigation 
has gone, it is present. In the Urodela, with the exception 
of Amphiuma, in which it is absent, it is a small insignifi- 
cant recess in the lagena and contains a small sense-organ. 
In the Anura it becomes a distinct part of the labyrinth 
with a w r ell developed sense-organ, closely related to the 
perilymphatic canal. In the Anurous Amphibia there also 
occurs a well developed middle ear, or tympanum, a struc- 
ture entirely wanting in the other members of the class 
and in the Fishes. 
Is the ear in the tailed amphibians an organ of hearing? 
This cannot as yet be answered very satisfactorily. A dis- 
tinct vocalizing apparatus is lacking in all but the Anur- 
ous Amphibia. Salamanders are notably silent creatures. 
John Burroughs, I believe, says that the Red Eft, that 
immature terrestrial form of Diemyctylus viridescens , pro- 
duces a musical sound, but it is undoubtedly not a true 
vocalization. This lack of vocalizing powers in the Sala- 
manders makes it very probable that they are defective in 
hearing. There being no tympanum present the ear cov- 
ered up by bone and muscle, cannot well respond to 
