and Structure of' the Proteus Anguinus. 21 



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 Jenestra 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 entu^ely 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 lacertlna 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 



