i 04 Observations on the Natural History 
The organ of hearing in the proteus is very simple. It has 
neither membrane nor cavity of the tympanum; but consists 
only of a large cavity formed in the bones of the cranium, in 
which is seen the little sac containing the ossicula or small bones : 
this cavity is also furnished with a fenestra ovalis , closed by a 
bony plate. On raising the little sac the semicircular membran- 
ous canals appeared to come into view, but of this the authors 
do not speak with confidence. This organ, as seen by them, is 
represented in Fig. 4., as above. 
The organ of smell in the proteus differs entirely in structure 
from that of the salamander, and the other animals of the same 
family ; and if we are entitled to infer the perfection of the sense 
from the structure of the organ, the proteus anguinus , in this 
respect, will surpass all other known reptiles. The external 
aperture of the nostrils is exceedingly small, and of a triangular 
form ; its position is represented in the profile view, Plate VI. 
Fig. 5., and corresponds internally with a canal that is soft and 
pulpy through its whole length. The olfactory nerves are rather 
large ; these nerves, after passing by the bulbs of the eyes, go 
out of the cranium, and divide and ramify on the soft substance 
that lines the nostrils. If with a needle the canal of the nostrils 
be broken down, and its substance removed, preserving at the 
same time the nervous filaments distributed upon it, the olfac- 
tory nerve is then resolved into a pencil of filaments, as deline- 
ated in Fig. 4. 
Conclusion. 
Having thus terminated the anatomical description of the 
Proteus Anguinus, the authors proceed to examine the two 
following questions ; firstly , Whether it be true, as many 
believe, that this reptile can respire, at the same time, by 
gills and by lungs ? Secondly , If the Sirena lacertina is to be 
regarded as a larva or a perfect animal ? To determine these 
questions, it will be necessary to compare the branchial struc- 
ture, the organs of circulation, and the supposed lungs of the 
proteus, with the corresponding parts in the sirena and in the 
larva of the salamander and of frogs. 
With respect to the branchial structure, there is a remark- 
able difference, not only as to form, but to texture, between the 
arches of the proteus, and those of the siren and larvae above 
mentioned. In the siren and larvae, the branchial arches are 
