J5S ON THE REIPIRATION OF FISHES. 



\ urodelas, bear more resemblance to the sharks; particular!/ 

 to that described by Schneider, and represented at fig. 31, 

 in his edition of Bloch's System of Ichthyology ; and which 

 he has termed ciliaris, because a portion of the gills appears 

 externally like a fringe. 

 The tadpole This period of^the life of batrachian reptilfes however is 



state sometimes not SO short, as has hitherto been supposed. Of this I have 

 had an opportunity of satisfying myself, having kept tad- 

 poles more than three years *. Yet when the lungs of these 

 animals are completely formed, their gills lost, and they 

 have only air to breath, there is hardly any thing altered oa 

 this account in their primitive organization, and they retain 

 as we may say their old mode of respiration. 

 Reptiles with 1* is well known, that the batrachian reptiles have no 



lungs, but no ribs, or at most only the rudiments of these bones : the 



ribs, breathe in , .1 ^ ^ . n 1 , 



a peculiar way. ^"ngs therefore must be inflated by some mechanism diffe- 

 rent from that of other animals. This was conjectured by 

 Herholdt and Rafn of Copenhagen, and almost immedi- 

 ately demonstrated by Cuvier and myself, though I have 

 since corrected, some of our former observations f. It is 



Some reptiles * It has been said, that most of the batrachian species undergo 

 slow in their their changes in one year: this is true with respect to the common 

 e anges. ^^.^g^ ^^^ edible frog, the green frog, the salamandre abdominale, 



and probably several othei*s. It is known however, that the rana 

 paradoxa is sometimes two years in the tadpole state; and 1 have 

 observed, that the young marbled lizards retain their gills more 

 than one year, having fed such in the spring. Besides, I have 

 kept in my house for three years tadpoles of the crapaud accoucheur, 

 whicli have constantly refused all kind of vegetable food, and 

 , which devoured one another, if they were not supplied with the 

 Hesh of animals. 

 Mode in which t There is neither valve nor valvulae within or at the base of the 

 the nostuls are nostrils, In ail the anouri, that have the tongue free and its root 

 attached to the cavity of the jaw, the two lobes apply themselves 

 to the interior orifice of the nose, so as to prevent the issue of the 

 air, or any other fluid contained in tire mouth, at the time of de- 

 glutition. In the urodeli, which have no tongue, two tubercles, an- 

 swering to the anterior bifurcation of the os hyoides, and covered 

 by the inner membrane of the mouth, apply themselves to the two 

 apertures of the nostrils, which are observed before the orbits of 

 the eyes, on opening the mouth of any of the salamanders, 



I10\T 



