REPTILES. 301 



to the mouth, it escapes rapidly through the branchial aper- 

 tures : nor is there any ground for believing that any por- 

 tion of it enters the very narrow clink of the glottis to pass 

 into this cavity, and from thence through the two membran- 

 ous canals to the air-bladders. No muscular structure suit- 

 ed to produce such effects exists, and the fine membranous 

 canals, subject to compression every instant from the sto- 

 mach, altogether unfit them for performing the office of air- 

 tubes or bronchi. In all reptiles that respire air, the struc- 

 ture of the organs is such as to permit free inspiration and 

 expiration, however different the form may be ; but in the 

 proteus, the want of ribs and diaphragm, the fact that the 

 nostrils do not open into the mouth, the extreme narrow- 

 ness of the aperture termed glottis, and the narrowness, 

 length, and compressibility of the air-tubes, all shew, that 

 in this animal none of those arrangements exist, which na- 

 ture has instituted with such great solicitude and skill in 

 other reptiles, to carry on with ease and certainty the re- 

 spiratory function. But it is needless to multiply arguments, 

 to prove that the air-bladders of these animals in nowise 

 perform the office of lungs, since it has been already shewn 

 that, when taken out of the water, they die just as fishes 

 do. 



" M. CUVIER justly observes, that those animals can alone 

 be deemed truly amphibious, ( qui respirent, a la fois, Pair 

 elastique en nature, et celui qui contient Feau :' and he then 

 goes on to state^ that the sirena lacertina respires through 

 its whole life by lungs and by gills, and is therefore a per- 

 manently amphibious animal ; but that the larvae of other 

 reptiles make use of these two different organs only for a 

 short period, and are therefore only temporarily amphibi- 

 ous. With all due respect, however, to so great a zoolo- 

 gist, we, say the authors, are of opinion, that before pro- 

 nouncing the siren to be permanently amphibious, it would 



